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Data Conversion Handbook

TEAM LinG - Live, Informative, Non-cost and Genuine !


Data Conversion Handbook

Walt Kester, Editor
with the technical staff of Analog Devices
A Volume in the Analog Devices Series

AMSTERDAM • BOSTON • HEIDELBERG • LONDON
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Contents
Foreword .......................................................................................................................... xvii
Preface ..............................................................................................................................xix
Acknowledgments ...............................................................................................................xxi
Chapter 1: Data Converter History ........................................................................................3
Section 1-1: Early History ............................................................................................................. 5
The Early Years: Telegraph to Telephone .......................................................................................... 6
The Invention of PCM ....................................................................................................................... 8
The Mathematical Foundations of PCM ........................................................................................... 9

The PCM Patents of Alec Harley Reeves ........................................................................................ 10
PCM and the Bell System: World War II through 1948 .................................................................. 11
Op Amps and Regenerative Repeaters: Vacuum Tubes to Solid-State ............................................ 13
Section 1-2: Data Converters of the 1950s and 1960s ................................................................... 19
Commercial Data Converters: 1950s ............................................................................................... 19
Commercial Data Converter History: 1960s ................................................................................... 20
Data Converter Architectures .......................................................................................................... 23
Section 1-3: Data Converters of the 1970s ................................................................................... 27
Monolithic Data Converters of the 1970s ........................................................................................ 28
Bipolar Process IC DACs of the 1970s ........................................................................................... 28
CMOS IC DACs of the 1970s ......................................................................................................... 29
Monolithic ADCs of the 1970s ........................................................................................................ 31
Hybrid Data Converters of the 1970s .............................................................................................. 32
Modular Data Converters of the 1970s ............................................................................................ 35
Section 1-4: Data Converters of the 1980s ................................................................................... 39
Monolithic DACs of the 1980s ........................................................................................................ 40
Monolithic ADCs of the 1980s ........................................................................................................ 41
Monolithic Flash ADCs of the 1980s .............................................................................................. 42
Hybrid and Modular DACs and ADCs of the 1980s ....................................................................... 42
Section 1-5: Data Converters of the 1990s ................................................................................... 45
Monolithic DACs of the 1990s ........................................................................................................ 46
Monolithic ADCs of the 1990s ........................................................................................................ 48
Hybrid and Modular DACs and ADCs of the 1990s ....................................................................... 52
Section 1-6: Data Converters of the 2000s ................................................................................... 53

Chapter 2: Fundamentals of Sampled Data Systems ...............................................................57
Section 2-1: Coding and Quantizing ............................................................................................. 57
Unipolar Codes ................................................................................................................................ 59
Gray Code ........................................................................................................................................ 61
Bipolar Codes .................................................................................................................................. 62

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Contents
Complementary Codes .................................................................................................................... 65
DAC and ADC Static Transfer Functions and DC Errors ............................................................... 66
Section 2-2: Sampling Theory ...................................................................................................... 73
The Need for a Sample-and-Hold Amplifier (SHA) Function ........................................................ 74
The Nyquist Criteria ........................................................................................................................ 76
Baseband Antialiasing Filters .......................................................................................................... 78
Undersampling (Harmonic Sampling, Bandpass Sampling, IF Sampling,
Direct IF-to-Digital Conversion) ................................................................................................. 80
Antialiasing Filters in Undersampling Applications ....................................................................... 81
Section 2-3: Data Converter AC Errors ........................................................................................ 83
Theoretical Quantization Noise of an Ideal N-Bit Converter .......................................................... 83
Noise in Practical ADCs .................................................................................................................. 88
Equivalent Input Referred Noise .................................................................................................... 89
Noise-Free (Flicker-Free) Code Resolution ................................................................................... 89
Dynamic Performance of Data Converters ...................................................................................... 90
Integral and Differential Nonlinearity Distortion Effects ................................................................ 90
Harmonic Distortion, Worst Harmonic, Total Harmonic Distortion (THD),
Total Harmonic Distortion Plus Noise (THD + N)...................................................................... 91
Signal-to-Noise-and-Distortion Ratio (SINAD), Signal-to-Noise Ratio (SNR),
and Effective Number of Bits (ENOB) ....................................................................................... 91
Analog Bandwidth ........................................................................................................................... 92
Spurious Free Dynamic Range (SFDR) .......................................................................................... 93
Two-Tone Intermodulation Distortion (IMD) ................................................................................. 94
Second- and Third-Order Intercept Points, 1 dB Compression Point ............................................. 95
Multitone Spurious Free Dynamic Range ....................................................................................... 96

Wideband CDMA (WCDMA) Adjacent Channel Power Ratio (ACPR) and Adjacent
Channel Leakage Ratio (ADLR) ................................................................................................. 97
Noise Power Ratio (NPR)................................................................................................................ 98
Noise Factor (F) and Noise Figure (NF) ....................................................................................... 100
Aperture Time, Aperture Delay Time, and Aperture Jitter ........................................................... 106
A Simple Equation for the Total SNR of an ADC ........................................................................ 108
ADC Transient Response and Overvoltage Recovery ................................................................... 109
ADC Sparkle Codes, Metastable States, and Bit Error Rate (BER) ............................................. 111
DAC Dynamic Performance ......................................................................................................... 115
DAC Settling Time ................................................................................................................. 115
Glitch Impulse Area ............................................................................................................... 116
DAC SFDR and SNR ............................................................................................................. 117
Measuring DAC SNR with an Analog Spectrum Analyzer .................................................... 118
DAC Output Spectrum and sin (x)/x Frequency Roll-off....................................................... 119
Oversampling Interpolating DACs ......................................................................................... 120
Section 2-4: General Data Converter Specifications...................................................................... 123
Overall Considerations .................................................................................................................. 123
Logic Interface Issues .................................................................................................................... 124
Data Converter Logic: Timing and other Issues ............................................................................ 125
Section 2-5: Defining the Specifications ....................................................................................... 127

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Contents

Chapter 3: Data Converter Architectures ............................................................................147
Section 3-1: DAC Architectures ................................................................................................. 147
DAC Output Considerations .......................................................................................................... 148

Basic DAC Structures .................................................................................................................... 149
The Kelvin Divider (String DAC) .......................................................................................... 149
Thermometer (Fully-Decoded) DACs .................................................................................... 151
Binary-Weighted DACs .......................................................................................................... 153
R-2R DACs............................................................................................................................. 155
Segmented DACs.................................................................................................................... 159
Oversampling Interpolating DACs ................................................................................................ 163
Multiplying DACs ......................................................................................................................... 164
Intentionally Nonlinear DACs ....................................................................................................... 164
Counting, Pulsewidth-Modulated (PWM) DACs .......................................................................... 167
Cyclic Serial DACs ........................................................................................................................ 167
Other Low Distortion Architectures .............................................................................................. 169
DAC Logic Considerations ............................................................................................................ 170
Section 3-2: ADC Architectures ................................................................................................. 175
The Comparator: A 1-Bit ADC...................................................................................................... 178
High Speed ADC Architectures ..................................................................................................... 180
Flash Converters ..................................................................................................................... 180
Successive Approximation ADCs........................................................................................... 185
Subranging, Error Corrected, and Pipelined ADCs ............................................................... 190
Serial Bit-Per-Stage Binary and Gray Coded (Folding) ADCs ............................................. 203
Counting and Integrating ADC Architectures ............................................................................... 211
A. H. Reeves’ 5-Bit Counting ADC ....................................................................................... 211
Charge Run-Down ADC......................................................................................................... 212
Ramp Run-Up ADC ............................................................................................................... 212
Tracking ADC ........................................................................................................................ 213
Voltage-to-Frequency Converters (VFCs) .............................................................................. 214
Dual Slope/Multislope ADCs ................................................................................................. 218
Optical Converters ......................................................................................................................... 220
Resolver-to-Digital Converters (RDCs) and Synchros .................................................................. 221
Section 3-3: Sigma-Delta Converters .......................................................................................... 231

Historical Perspective .................................................................................................................... 231
Sigma-Delta (Σ-∆) or Delta-Sigma (∆-Σ)? ................................................................................... 234
Basics of Sigma-Delta ADCs ........................................................................................................ 235
Idle Tone Considerations ............................................................................................................... 240
Higher Order Loop Considerations ............................................................................................... 241
Multibit Sigma-Delta Converters .................................................................................................. 242
Digital Filter Implications ............................................................................................................. 243
Multistage Noise Shaping (MASH) Sigma-Delta Converters ....................................................... 244
High Resolution Measurement Sigma-Delta ADCs ...................................................................... 245
Sigma-Delta DACs ........................................................................................................................ 249

Chapter 4: Data Converter Process Technology ....................................................................257
Section 4-1: Early Processes ...................................................................................................... 257
Vacuum Tube Data Converters ...................................................................................................... 257
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Contents
Solid State, Modular, and Hybrid Data Converters ....................................................................... 259
Calibration Processes..................................................................................................................... 262
Section 4-2: Modern Processes................................................................................................... 265
Bipolar Processes........................................................................................................................... 265
Thin Film Resistor Processes ........................................................................................................ 265
Complementary Bipolar (CB) Processes ....................................................................................... 266
CMOS Processes ........................................................................................................................... 266
Data Converter Processes and Architectures ................................................................................. 268
Section 4-3: Smart Partitioning ................................................................................................. 273
When Complete Integration Isn’t the Optimal Solution ................................................................ 273
Why Smart Partitioning is Necessary ........................................................................................... 276

What’s Changing? ......................................................................................................................... 277

Chapter 5: Testing Data Converters ...................................................................................283
Section 5-1: Testing DACs ........................................................................................................ 283
Static DAC Testing ........................................................................................................................ 283
End-Point Errors ..................................................................................................................... 284
Linearity Errors ...................................................................................................................... 286
Superposition and DAC Errors ............................................................................................... 286
Measuring DAC DNL and INL Using Superposition ............................................................ 287
Measuring DAC INL and DNL Where Superposition Does Not Hold .................................. 290
Testing DACs for Dynamic Performance ...................................................................................... 292
Settling Time .......................................................................................................................... 292
Glitch Impulse Area ............................................................................................................... 293
Oscilloscope Measurement of Settling Time and Glitch Impulse Area ................................ 294
Distortion Measurements ....................................................................................................... 295
Section 5-2: Testing ADCs ........................................................................................................ 303
A Brief Historical Overview of Data Converter Specifications and Testing ................................. 303
Static ADC Testing ........................................................................................................................ 304
Back-to-Back Static ADC Testing .......................................................................................... 306
Crossplot Measurements of ADC Linearity ........................................................................... 309
Servo-Loop Code Transition Test ........................................................................................... 310
Computer-Based Servo-Loop ADC Tester ............................................................................. 311
Histogram (Code Density) Test with Linear Ramp Input ...................................................... 312
Dynamic ADC Testing................................................................................................................... 317
Manual “Back-to-Back” Dynamic ADC Testing ................................................................... 317
Measuring Effective Number of Bits (ENOB) Using Sinewave Curve Fitting ...................... 320
FFT Basics.............................................................................................................................. 322
FFT Test Setup Configuration and Measurements ................................................................. 329
Verifying the FFT Accuracy ................................................................................................... 335
Generating Low Distortion Sinewave Inputs ......................................................................... 335

Noise Power Ratio (NPR) Testing .......................................................................................... 337
Measuring ADC Aperture Jitter Using the Locked-Histogram Test Method ......................... 338
Measuring Aperture Delay Time ............................................................................................ 340
Measuring ADC Aperture Jitter Using FFTs.......................................................................... 340
Measuring ADC Analog Bandwidth Using FFTs .................................................................. 342
Settling Time .......................................................................................................................... 343
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Contents
Overvoltage Recovery Time ................................................................................................... 344
Video Testing, Differential Gain and Differential Phase ........................................................ 344
Bit Error Rate (BER) Tests ..................................................................................................... 348

Chapter 6: Interfacing to Data Converters...........................................................................359
Section 6-1: Driving ADC Analog Inputs ..................................................................................... 359
Amplifer DC and AC Performance Considerations ...................................................................... 361
Rail-Rail Input Stages.................................................................................................................... 362
Output Stages................................................................................................................................. 365
Gain and Level-Shifting Circuits Using Op Amps ........................................................................ 367
Op Amp AC Specifications and Data Converter Requirements .................................................... 369
Driving High Resolution Σ-∆ Measurement ADCs ....................................................................... 371
Driving Single-Ended Input Single-Supply 1.6 V to 3.6 V Successive Approximation ADCs ..... 372
Driving Single-Supply ADCs with Scaled Inputs ......................................................................... 373
Driving Differential Input CMOS Switched Capacitor ADCs ...................................................... 374
Single-Ended Drive Circuits for Differential Input CMOS ADCs ................................................ 376
Differential Input ADC Drivers ..................................................................................................... 378
Driving ADCs with Differential Amplifiers .................................................................................. 382
Dual Op Amp Drivers .................................................................................................................... 383

Fully Integrated Differential Amplifier Drivers ............................................................................. 384
Driving Differential Input ADCs with Integrated Differential Drivers ......................................... 387
Section 6-2: ADC and DAC Digital Interfaces(and Related Issues) ................................................ 397
Power-On Initialization of Data Converters ................................................................................. 397
Initialization of Data Converter Internal Control Registers........................................................... 398
Low Power, Sleep, and Standby Modes ....................................................................................... 398
Single-Shot Mode, Burst Mode, and Minimum Sampling Frequency .......................................... 399
ADC Digital Output Interfaces ...................................................................................................... 400
ADC Serial Output Interfaces ....................................................................................................... 400
ADC Serial Interface to DSPs ...................................................................................................... 403
ADC Parallel Output Interfaces ..................................................................................................... 405
DAC Digital Input Interfaces ......................................................................................................... 408
DAC Serial Input Interfaces to DSPs ............................................................................................ 410
DAC Parallel Input Interfaces to DSPs .......................................................................................... 411
Section 6-3: Buffering DAC Analog Outputs ............................................................................... 415
Differential to Single-Ended Conversion Techniques ................................................................... 416
Single-Ended Current-to-Voltage Conversion ............................................................................... 418
Differential Current-to-Differential Voltage Conversion ............................................................... 420
An Active Low-Pass Filter for Audio DAC .................................................................................. 420
Section 6-4: Data Converter Voltage References .......................................................................... 423
Section 6-5: Sampling Clock Generation ..................................................................................... 427
Oscillator Phase Noise and Jitter ................................................................................................... 430
“Hybrid” Clock Generators ........................................................................................................... 437
Driving Differential Sampling Clock Inputs ................................................................................. 438
Sampling Clock Summary ............................................................................................................. 439

Chapter 7: Data Converter Support Circuits ........................................................................443
Section 7-1: Voltage References ................................................................................................. 443
Precision Voltage References ........................................................................................................ 443
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Contents
Types of Voltage References.......................................................................................................... 444
Bandgap References ............................................................................................................... 446
Buried Zener References ........................................................................................................ 451
XFET References ................................................................................................................... 452
Voltage Reference Specifications .................................................................................................. 455
Tolerance ................................................................................................................................ 455
Drift ........................................................................................................................................ 455
Supply Range ......................................................................................................................... 456
Load Sensitivity ...................................................................................................................... 456
Line Sensitivity....................................................................................................................... 457
Noise....................................................................................................................................... 457
Scaled References .......................................................................................................................... 459
Voltage Reference Pulse Current Response................................................................................... 460
Low Noise References for High Resolution Converters ............................................................... 462
Section 7-2: Low Dropout Linear Regulators ............................................................................... 465
Linear Voltage Regulator Basics.................................................................................................... 465
Pass Devices and their Associated Trade Offs ............................................................................... 468
Low Dropout Regulator Architectures .......................................................................................... 472
The anyCAP Low Dropout Regulator Family ............................................................................... 475
Design Features Related to DC Performance ......................................................................... 475
Design Features Related to AC Performance ......................................................................... 476
A Basic Pole-Splitting Topology ............................................................................................ 477
The anyCAP Pole-Splitting Topology .................................................................................... 477
The anyCAP LDO series devices ........................................................................................... 478
Functional Diagram and Basic 50 mA LDO Regulator ......................................................... 479
LDO Regulator Thermal Considerations ............................................................................... 481

LDO Regulator Controllers ........................................................................................................... 485
Regulator Controller Differences ........................................................................................... 485
A Basic 5 V/1 A LDO Regulator Controller .......................................................................... 486
Selecting the Pass Device ....................................................................................................... 487
Thermal Design ...................................................................................................................... 488
Sensing Resistors for LDO Controllers .................................................................................. 489
PCB Layout Issues ................................................................................................................. 490
A 2.8 V/8 A LDO Regulator Controller ................................................................................. 491
Section 7-3: Analog Switches and Multiplexers ............................................................................ 493
CMOS Switch Basics .................................................................................................................... 494
Error Sources in the CMOS Switch............................................................................................... 496
Applying the Analog Switch ........................................................................................................ 504
1 GHz CMOS Switches ................................................................................................................. 508
Video Switches and Multiplexers .................................................................................................. 508
Video Crosspoint Switches ............................................................................................................ 511
Digital Crosspoint Switches .......................................................................................................... 512
Switch and Multiplexer Families from Analog Devices................................................................ 512
Parasitic Latchup in CMOS Switches and Muxes ......................................................................... 512
Section 7-4: Sample-and-Hold Circuits ........................................................................................ 519
Introduction and Historical Perspective ........................................................................................ 519
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Contents
Basic SHA Operation .................................................................................................................... 521
Track Mode Specifications ............................................................................................................ 522
Track-to-Hold Mode Specifications .............................................................................................. 522
Hold Mode Specifications ............................................................................................................. 526
Hold-to-Track Transition Specifications ....................................................................................... 528

SHA Architectures ......................................................................................................................... 529
Internal SHA Circuits for IC ADCs............................................................................................... 531
SHA Applications .......................................................................................................................... 533

Chapter 8: Data Converter Applications .............................................................................539
Section 8-1: Precision Measurement and Sensor Conditioning ........................................................ 539
Applications of Precision Measurement Σ-∆ ADCs ...................................................................... 540
Weigh Scale Design Analysis Using the AD7730 ADC ................................................................ 544
Thermocouple Conditioning Using the AD7793 ........................................................................... 549
Direct Digital Temperature Measurements.................................................................................... 551
Microprocessor Substrate Temperature Sensors............................................................................ 555
Applications of ADCs in Power Meters ........................................................................................ 558
Section 8-2: Multichannel Data Acquisition Systems..................................................................... 563
Data Acquisition System Configurations....................................................................................... 563
Multiplexing .................................................................................................................................. 564
Filtering Considerations in Data Acquisition Systems .................................................................. 567
Complete Data Acquisition Systems on a Chip ............................................................................. 568
Multiplexing Inputs to Σ-∆ ADCs ................................................................................................. 570
Simultaneous Sampling Systems ................................................................................................... 572
Data Distribution Systems ............................................................................................................ 574
Data Distribution Using an Infinite Sample-and-Hold .................................................................. 578
Section 8-3: Digital Potentiometers ............................................................................................ 581
Modern Digital Potentiometers in Tiny Packages ......................................................................... 582
Digital Potentiometers with Nonvolatile Memory ........................................................................ 584
One-Time Programmable (OTP) Digital Potentiometers .............................................................. 585
Digital Potentiometer AC Considerations ..................................................................................... 586
Application Examples ................................................................................................................... 587
Section 8-4: Digital Audio ......................................................................................................... 591
Sampling Rate and THD + N Requirements for Digital Audio..................................................... 592
Overall Trends in Digital Audio ADCs and DACs ........................................................................ 595

Voiceband Codecs.......................................................................................................................... 596
High Performance Audio ADCs and DACs in Separate Packages ................................................ 597
High Performance Multichannel Audio Codecs and DACs .......................................................... 600
Sample Rate Converters ................................................................................................................ 602
Section 8-5: Digital Video and Display Electronics ....................................................................... 607
Digital Video .................................................................................................................................. 607
Digital Video Formats ............................................................................................................ 608
Serial Data Interfaces ............................................................................................................. 612
Digital Video ADCs and DACs: Decoders, and Encoders ..................................................... 612
Specifications for Video Decoders and Encoders ................................................................... 614
Display Electronics ........................................................................................................................ 615
Flat Panel Display Electronics ............................................................................................... 619
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Contents
CCD Imaging Electronics ...................................................................................................... 622
Touchscreen Digitizers ........................................................................................................... 627
Section 8-6: Software Radio and IF Sampling .............................................................................. 633
Evolution of Software Radio ......................................................................................................... 634
A Receiver Using Digital Processing at Baseband ........................................................................ 635
Narrowband IF-Sampling Digital Receivers ................................................................................. 636
Wideband IF-Sampling Digital Receivers ..................................................................................... 639
Increasing ADC Dynamic Range Using Dither............................................................................. 649
Wideband Radio Transmitter Considerations ................................................................................ 655
Cellular Telephone Handsets ......................................................................................................... 659
The Role of ADCs and DACs in Cellular Telephone Handsets..................................................... 661
SoftFone® and Othello Radio Chipsets from Analog Devices ..................................................... 662
Time-Interleaved IF Sampling ADCs with Digital Post-Processors ............................................. 667

Advanced Digital Post Processing ................................................................................................. 671
Advanced Filter Bank (AFB) ........................................................................................................ 672
AFB Design Example: The AD12400 12-Bit, 400 MSPS ADC ................................................... 673
Section 8-7: Direct Digital Synthesis (DDS) ................................................................................ 677
Introduction to DDS ...................................................................................................................... 677
Aliasing in DDS Systems .............................................................................................................. 681
Frequency Planning in DDS Systems............................................................................................ 682
Modern Integrated DDS Systems .................................................................................................. 684
Section 8-8: Precision Analog Microcontrollers ............................................................................ 693
Characteristics of the MicroConverter Product Family ................................................................. 694
Some Σ-∆ MicroConverter Applications ....................................................................................... 700
ADuC7xxx MicroConverter Products Based on the ARM7 Processor Core ................................ 702

Chapter 9: Hardware Design Techniques .............................................................................709
Section 9-1: Passive Components ............................................................................................... 711
Capacitors ...................................................................................................................................... 711
Dielectric Absorption ............................................................................................................. 712
Capacitor Parasitics and Dissipation Factor ........................................................................... 714
Tolerance, Temperature, and Other Effects ............................................................................ 715
Assemble Critical Components Last ...................................................................................... 715
Resistors and Potentiometers ......................................................................................................... 718
Resistor Parasitics................................................................................................................... 720
Thermoelectric Effects ........................................................................................................... 720
Voltage Sensitivity, Failure Mechanisms, and Aging ............................................................. 722
Resistor Excess Noise ............................................................................................................ 723
Potentiometers ........................................................................................................................ 723
Inductance...................................................................................................................................... 725
Stray Inductance ..................................................................................................................... 725
Mutual Inductance .................................................................................................................. 725
Ringing ................................................................................................................................... 728

Parasitic Effects in Inductors .................................................................................................. 728
Q or “Quality Factor” ............................................................................................................. 729
Don’t Overlook Anything .............................................................................................................. 729

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Contents
Section 9-2: PC Board Design Issues .......................................................................................... 733
Resistance of Conductors .............................................................................................................. 733
Voltage Drop in Signal Leads—“Kelvin” Feedback ..................................................................... 735
Signal Return Currents .................................................................................................................. 736
Grounding in Mixed Analog/Digital Systems ............................................................................... 737
Ground and Power Planes ...................................................................................................... 738
Double-Sided versus Multilayer Printed Circuit Boards ........................................................ 739
Multicard Mixed-Signal Systems ........................................................................................... 740
Separating Analog and Digital Grounds................................................................................. 740
Grounding and Decoupling Mixed-Signal ICs with Low Digital Currents ........................... 742
Treat the ADC Digital Outputs with Care .............................................................................. 743
Sampling Clock Considerations ............................................................................................. 744
The Origins of the Confusion about Mixed-Signal Grounding: Applying Single-Card
Grounding Concepts to Multicard Systems ...................................................................... 746
Summary: Grounding Mixed-Signal Devices with Low Digital Currents in a
Multicard System ............................................................................................................... 747
Summary: Grounding Mixed-Signal Devices with High Digital Currents in a
Multicard System ............................................................................................................... 748
Grounding DSPs with Internal Phase-Locked Loops............................................................. 748
Grounding Summary .............................................................................................................. 749
Some General PC Board Layout Guidelines for Mixed-Signal Systems ...................................... 750

Skin Effect .............................................................................................................................. 751
Transmission Lines................................................................................................................. 753
Be Careful With Ground Plane Breaks................................................................................... 753
Ground Isolation Techniques.................................................................................................. 754
Static PCB Effects .................................................................................................................. 756
Sample MINIDIP and SOIC Op Amp PCB Guard Layouts .................................................. 758
Dynamic PCB Effects ............................................................................................................ 760
Stray Capacitance ................................................................................................................... 761
Capacitive Noise and Faraday Shields ................................................................................... 762
The Floating Shield Problem.................................................................................................. 762
Buffering ADCs Against Logic Noise ................................................................................... 763
Section 9-3: Analog Power Supply Systems.................................................................................. 767
Linear IC Regulation ..................................................................................................................... 768
Some Linear Voltage Regulator Basics .................................................................................. 768
Pass Devices .......................................................................................................................... 770
±15 V Regulator Using Adjustable Voltage ICs ..................................................................... 770
Low Dropout Regulator Architectures ................................................................................... 771
Fixed-Voltage, 50/100/200/500/1000/1500 mA LDO Regulators ......................................... 772
Adjustable Voltage, 200 mA LDO Regulator ......................................................................... 774
Charge-Pump Voltage Converters ................................................................................................. 775
Regulated Output Charge-Pump Voltage Converters .................................................................... 776
Linear Post Regulator for Switching Supplies .............................................................................. 778
Grounding Linear and Switching Regulators ................................................................................ 779
Power Supply Noise Reduction and Filtering ............................................................................... 782
Capacitors ............................................................................................................................... 782
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Contents

Ferrites .................................................................................................................................... 786
Card Entry Filter..................................................................................................................... 787
Rail Bypass/Distribution Filter ............................................................................................... 788
Local High Frequency Bypass/Decoupling ............................................................................ 789
Section 9-4: Overvoltage Protection ........................................................................................... 793
In-Circuit Overvoltage Protection ................................................................................................. 793
General Input Common Mode Limitations ................................................................................... 793
Clamping Diode Leakage .............................................................................................................. 795
A Flexible Voltage Follower Protection Circuit ........................................................................... 796
Common-Mode Overvoltage Protection Using CMOS Channel Protectors ................................. 797
CM Overvoltage Protection Using High CM Voltage In Amp ...................................................... 798
Inverting Mode Op Amp Protection Schemes ............................................................................... 800
Amplifier Output Voltage Phase-Reversal ..................................................................................... 800
An Output Phase-Reversal Do-it-Yourself Test...................................................................... 802
Fixes for Output Phase–Reversal ........................................................................................... 802
Input Differential Protection ......................................................................................................... 803
Protecting In Amps Against Overvoltage ...................................................................................... 804
Overvoltage Protection Using CMOS Channel Protectors............................................................ 808
Digital Isolators ............................................................................................................................. 810
Out-of-Circuit Overvoltage Protection .......................................................................................... 813
ESD Models and Testing ............................................................................................................... 817
Section 9-5: Thermal Management ............................................................................................. 823
Thermal Basics .............................................................................................................................. 823
Heat Sinking .................................................................................................................................. 825
Data Converter Thermal Considerations ....................................................................................... 829
Section 9-6: EMI/RFI Considerations ......................................................................................... 833
EMI/RFI Mechanisms ................................................................................................................... 834
EMI Noise Sources ........................................................................................................................ 834
EMI Coupling Paths ...................................................................................................................... 834
Noise Coupling Mechanisms ......................................................................................................... 834

Reducing Common-Impedance Noise ........................................................................................... 835
Noise Induced by Near-Field Interference .................................................................................... 836
Reducing Capacitance-Coupled Noise .......................................................................................... 836
Reducing Magnetically-Coupled Noise ........................................................................................ 837
Passive Components: Your Arsenal Against EMI .......................................................................... 838
Reducing System Susceptibility to EMI........................................................................................ 839
A Review of Shielding Concepts ................................................................................................... 839
General Points on Cables and Shields ........................................................................................... 842
Input-Stage RFI Rectification Sensitivity ...................................................................................... 846
Background: Op Amp and In Amp RFI Rectification Sensitivity Tests ................................. 846
An Analytical Approach: BJT RFI Rectification.................................................................... 847
An Analytical Approach: FET RFI Rectification .................................................................. 848
Reducing RFI Rectification Within Op amp and In Amp Circuits ......................................... 849
Op Amp Inputs ............................................................................................................................. 849
In Amp Inputs ................................................................................................................................ 850
Amplifier Outputs and EMI/RFI ................................................................................................... 852
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Contents
Printed Circuit Board Design for EMI/RFI Protection.................................................................. 852
Choose Logic Devices Carefully .................................................................................................. 853
Design PCBs Thoughtfully............................................................................................................ 853
Designing Controlled Impedances Traces on PCBs ..................................................................... 854
Microstrip PCB Transmission Lines ............................................................................................. 855
Some Microstrip Guidelines .......................................................................................................... 855
Symmetric Stripline PCB Transmission Lines .............................................................................. 856
Some Pros and Cons of Embedding Traces ................................................................................... 857
Dealing with High-Speed Logic .................................................................................................... 858

Section 9-7: Low Voltage Logic Interfacing .................................................................................. 867
Voltage Tolerance and Voltage Compliance .................................................................................. 870
Interfacing 5 V Systems to 3.3 V Systems using NMOS FET “Bus Switches” ............................ 871
3.3 V/2.5 V Interfaces .................................................................................................................... 873
3.3 V/2.5 V, 3.3 V/1.8 V, 2.5 V/1.8 V Interfaces ............................................................................ 874
Hot Swap and Hot Plug Applications of Bus Switches ................................................................. 878
Internally Created Voltage Tolerance / Compliance ...................................................................... 879
Section 9-8: Breadboarding and Prototyping ............................................................................... 881
“Deadbug” Prototyping ................................................................................................................. 882
Solder-Mount Prototyping ............................................................................................................. 884
Milled PCB Prototyping ................................................................................................................ 885
Beware of Sockets ......................................................................................................................... 886
Some Additional Prototyping Points ............................................................................................. 887
Evaluation Boards.......................................................................................................................... 887
General-Purpose Op Amp Evaluation Board from the Mid-1990s ........................................ 888
Dedicated Op Amp Evaluation Boards .................................................................................. 888
Data Converter Evaluation Boards ......................................................................................... 890

Index ...............................................................................................................................895

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Foreword
The signal-processing products of Analog Devices (and its worthy competitors) have always had broad applications, but in a special way: they tend to be used in critical roles making possible—and at the same time
limiting—the excellence in performance of the device, instrument, apparatus, or system using them.
Think about the op amp—how it can play a salient role in amplifying an ultrasound wave from deep within
a human body, or measure and help reduce the error of a feedback system; the data converter—and its
critical position in translating rapidly and accurately between the world of tangible physics and the world of

abstract digits; the digital signal processor—manipulating the transformed digital data to extract information, provide answers, and make crucial instant-by-instant decisions in control systems; transducers, such
as the life-saving MEMS accelerometers and gyroscopes; and even control chips, such as the one that
empowers the humble thermometric junction placed deep in the heart of a high-performance—but very
vulnerable—microcomputer chip.
From its founding two human generations ago, in 1965, Analog Devices has been committed to a leadership role in designing and manufacturing products that meet the needs of the existing market, anticipate the
near-term needs of present and future users, and envision the needs of users yet unknown—and perhaps
unborn—who will create the markets of the future. These existing, anticipated and envisioned “needs” must
perforce include far more than just the design, manufacture and timely delivery of a physical device that
performs a function reliably to a set of specifications at a competitive price.
We’ve always called a product that satisfies these needs “the augmented product,” but what does this mean?
The physical product is a highly technological product that, above all, requires knowledge of its possibilities, limitations and subtleties. But when the earliest generations—and to some extent later generations—of
such a product appear in the marketplace, there exist few (if any) school courses that have produced graduates proficient in its use. There are few knowledgeable designers who can foresee its possibilities. So we
have the huge task of creating awareness; teaching about principles, performance measures, and existing
applications; and providing ideas to stimulate the imagination of those creative users who will provide our
next round of challenges.
This problem is met by deploying people and publications. The people are Applications Engineers, who can
deal with user questions arriving via phone, fax, and e-mail—as well as working with users in the field to
solve particular problems. These experts also spread the word by giving seminars to small and large groups
for purposes from inspiring the creative user to imbuing the system, design, and components engineer with
the nuts-and-bolts of practice. The publications—both in hard copy and on-line—range from authoritative
handbooks, such as the present volume, comprehensive data sheets, application notes, hardware and software manuals, to periodic publications, such as “Solutions Bulletins” and our unique Analog Dialogue—the
sole survivor among its early peers—currently approaching its 39th year of continuous publication in print
and its 7th year of regular publication on the Internet.
This book is the ultimate expression of product “augmentation” as it relates to data converters. It can be
considered a direct descendant of the Analog Devices 1972 Analog-Digital Conversion Handbook, edited
by the undersigned. This timely publication was seminal in the early days of the mini- and microcomputer
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Foreword
era—advocating the understanding and use of data converters and their links to an IC computer market
that was then on the verge of explosive growth. Its third—and most recent—edition was published nearly
20 years ago, in 1986.
Data converters have been marketed as board-mountable components since the mid- to late 1960s, and practical IC D/A and A/D converters have been available since the mid-’70s. Yet, a third of a century later, there
is still a need for a book that embraces the many aspects of conversion technology—one that is thorough in
its technical content, that looks forward to tomorrow’s uses and back to the principles and applications that
still make data converters a vital necessity today. This is indeed such a book, and I am delighted that Walt
Kester continues the practice of “augmenting” our data converters in such an interesting and accessible form.
Dan Sheingold, August 24, 2004
Norwood, Massachusetts

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Preface
This book is written for the practicing design engineer who must routinely use data converters and related
support circuitry. We have therefore included many practical design suggestions. Much of the material has
been taken—and updated where necessary—from previous popular Analog Devices’ seminar books. Most
of the tutorial sections have undergone several revisions over the years to ensure their accuracy and clarity.
Various highly experienced members of the Analog Devices’ technical staff have contributed to the material, and they are recognized at the beginning of each major section in the book.
Chapter 1, Data Converter History, covers the chronological history of data converters. The chapter covers
the period starting from the invention of the telegraph to the present time, and focuses on the hardware
evolution of data converters. The history of data converter architectures is covered in Chapter 3, Data Converter Architectures, along with the descriptions of the various architectures themselves. A history of data
converter processes is included in Chapter 4, Data Converter Process Technology, and the history of data
converter testing is included as part of Chapter 5, Testing Data Converters.
Chapter 2, Fundamentals of Sampled Data Systems, contains the basics of coding, sampling, and quantizing. The various static and dynamic data converter error sources as well as specification definitions are also
included in this chapter.
Chapter 3, Data Converter Architectures, includes not only architecture descriptions but a historical perspective on the popular DAC and ADC topologies. This chapter includes descriptions of both high and low

speed ADC architectures as well as sigma-delta data converters.
Chapter 4, Data Converter Process Technology, takes a look at the various processes used to produce data
converters, including a brief historical perspective. The chapter concludes with a discussion on “smart partitioning” of systems to achieve the maximum performance at the lowest cost.
Chapter 5, Testing Data Converters, includes both classic and modern techniques for testing data static and
dynamic data converter performance, including a brief history of data converter testing. Of particular interest to modern applications is the relatively non-mathematical section on FFT testing.
Chapter 6, Interfacing to Data Converters, discusses solutions to various interface problems associated
with data converters. The chapter begins with a study of the ADC analog inputs, and the various methods
available for achieving optimum performance. Details of the digital interface to data converters are treated
in a general manner, and various DAC output buffer configurations are presented. The chapter ends with a
discussion of the critical issue of generating low jitter sampling clocks.
Chapter 7, Data Converter Support Circuits, covers various external components required to support data
converters and data acquisition systems, including voltage references, regulators, analog switches and
multiplexers, and sample-and-holds. Even though many of these function are incorporated into modern data
converters, a fundamental understanding of them is useful to the system design engineer.
Chapter 8, Data Converter Applications, concentrates on specific data converter applications, including precision measurement and sensor conditioning, multichannel data acquisition systems, digital potentiometers,
digital audio, digital video and display electronics, software radio and IF sampling, direct digital synthesis,
and precision analog microcontrollers.

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Preface
The material contained in Chapter 9, Hardware Design Techniques—the longest chapter in the book—has
always been the most popular topic in the Analog Devices seminar series and probably contains the most
important material in the entire book regarding practical issues in using data converters and their related
components. The chapter begins with a thorough discussion of various pitfalls and solutions relating to the
non-ideal qualities of passive components—capacitors, resistors, and inductors.
The section of Chapter 9, PC Board Design Issues, covers the important topics of grounding, layout, and
decoupling. The recommendations presented reflect the collective inputs of a large number of experienced

design and applications engineers at Analog Devices whose experience in data converters spans several decades.
Another key section in Chapter 9 is Analog Power Supply Systems, where the issues of generating clean
analog supply voltages are addressed. Considerations for both linear and switching regulators are covered
in the section.
Circuits used in data acquisition systems are often connected to external sensors and are therefore subject to
overvoltage conditions. The section on Overvoltage Protection in Chapter 9 includes a discussion of the impact of overvoltage on ICs as well as methods for protecting critical analog circuits. The section concludes
with a brief description of electrostatic discharge (ESD), including models and testing.
The Thermal Management section in Chapter 9 is especially important when dealing with devices which
dissipate more than a few hundred milliwatts of power. The section covers the basics of thermal calculations using the traditional thermal resistance analysis. Methods for heatsinking high power devices, such as
series pass transistors used in high current linear voltage regulators, are also discussed.
In the section titled EMI/RFI Considerations, the basics principles of EMI/RFI are first discussed, including
EMI/RFI mechanisms, noise sources, coupling paths, near and far-field interference. The next part of the
section contains a discussion of how passive components can be used to minimize EMI/RFI problems. A
review of shielding concepts follows, and the general issue of RFI rectification is covered. PC board layout
techniques useful in combating EMI/RFI problems conclude the section.
The section on Low Voltage Logic Interfacing deals with the common problem of interfacing devices in
systems which operate on multiple supply voltages.
Chapter 9 concludes with a discussion of breadboarding and prototyping techniques as well as the general
use of manufacturer’s evaluation boards.

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Acknowledgments
Thanks are due the many technical staff members of Analog Devices in Engineering, Marketing, and Applications who provided invaluable inputs during this project. Particular credit is give to the individual authors
whose names appear at the beginning of their material.
Dan Sheingold graciously provided material from his classic 1986, Analog-Digital Conversion Handbook.
Over the years, Dan has truly set the standards for technical publication quality, not only with Analog
Dialogue, but with many other Analog Devices’ technical books.

Special thanks also go to Brad Brannon, Wes Freeman, Walt Jung, Bob Marwin, Hank Zumbahlen, and
Scott Wayne who reviewed the material for accuracy.
Judith Douville compiled the index and also offered many helpful manuscript comments.
A thank you also goes to ADI management, especially Dave Kress, for encouragement and support of the
project.
Walt Kester, May 2004
Central Applications Department, Analog Devices
Direct questions, corrections, and comments to , with a subject line of “Data
Conversion Handbook.”

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CH A PTE R 1

Data Converter History
■

Section 1-1: Early History

■

Section 1-2: Data Converters of the 1950s
and 1960s

■

Section 1-3: Data Converters of the 1970s


■

Section 1-4: Data Converters of the 1980s

■

Section 1-5: Data Converters of the 1990s

■

Section 1-6: Data Converters of the 2000s

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CHAPTE R 1

Data Converter History
Walt Kester
Chapter Preface
This chapter was inspired by Walt Jung’s treatment of op amp history in his book, Op Amp Applications
Handbook (Reference 1). His writing on the subject contains references to hundreds of interesting articles,
patents, etc., which taken as a whole, paints a fascinating picture of the development of the operational
amplifier—from Harold Black’s early feedback amplifier sketch to modern high performance IC op amps.
We have attempted to do the same for the history of data converters. In considering the scope of this
effort—and the somewhat chaotic and fragmented development of data converters—we were faced with a
difficult challenge in organizing the material. Rather than putting all the historical material in this single
chapter, we have chosen to disperse some of it throughout the book. For instance, most of the historical
material related to data converter architectures is included in Chapter 3 (Data Converter Architectures).
along with the individual converter architectural descriptions. Likewise, Chapter 4 (Data Converter Process

Technology) includes most of the key events related to data converter process technology. Chapter 5 (Testing Data Converters) touches on some of the key historical developments relating to data converter testing.
In an effort to make each chapter of this book stand on its own as much as possible, some of the historical
material is repeated in several places—therefore, the reader should realize that this repetition is intentional
and not the result of careless editing.

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SE CTION 1- 1

Early History
It is difficult to determine exactly when the first data converter was made or what form it took. The earliest recorded binary DAC known to the authors of this book is not electronic at all, but hydraulic. Turkey,
under the Ottoman Empire, had problems with its public water supply, and sophisticated systems were built
to meter water. One of these is shown in Figure 1.1 and dates to the 18th century. An example of an actual
dam using this metering system was the Mahmud II dam built in the early 19th century near Istanbul and
described in Reference 2.
The metering system used reservoirs (labeled header tank in the diagrams) maintained at a constant depth
(corresponding to the reference potential) by means of a spillway over which water just trickled (the
criterion was sufficient flow to float a straw). This is illustrated in Figure 1.1A. The water output from the
header tank is controlled by gated binary-weighted nozzles submerged 96 mm below the surface of the
water. The output of the nozzles feeds an output trough as shown in Figure 1.1B. The nozzle sizes corresponded to flows of binary multiples and submultiples of the basic unit of 1 lüle (= 36 l/min or 52 m3/day).
An eight-lüle nozzle was known as a “sekizli lüle,” a four lüle nozzle a “dörtlü lüle,” a ¼ lüle nozzle a
“kamus,,” an eighth lüle a “masura,” and a thirty-second lüle a “çuvaldiz.” Details of the metering system
using the binary weighted nozzles are shown in Figure 1.1C. Functionally this is an 8-bit DAC with manual
(rather than digital, no doubt) input and a wet output, and it may be the oldest DAC in the world. There are
probably other examples of early data converters, but we will now turn our attention to those based on more
familiar electronic techniques.

NOZZLES

96mm
HEADER
TANK

WATER
LEVEL

SPILLWAY
96mm

HEADER
TANK

WATER
INPUT
FROM
DAM

OUTPUT
TROUGH

NOZZLES
(A) HEADER SYSTEM: Note: The spillway
and the nozzles need different outlets

(C) TOP VIEW OF
METERING SYSTEM
DETAILS SHOWING
BINARY WEIGHTED
NOZZLES

Adapted from:
Kâzim Çeçen, “Sinan's Water Supply
System in Istanbul,” Istanbul Technical University/
Istanbul Water and Sewage Administration,
Istanbul Turkey, 1992−1993, pp. 165−167.

(B) SECTIONAL VIEW OF METERING SYSTEM

8 BINARY
WEIGHTED
NOZZLES

HEADER
TANK

WATER
INPUT
FROM
DAM

OUTPUT
TROUGH
SPILLWAY

Figure 1.1: Early 18th Century Binary Weighted Water Metering System

Probably the single largest driving force behind the development of electronic data converters over the
years has been the field of communications. The telegraph led to the invention of the telephone, and the
subsequent formation of the Bell System. The proliferation of the telegraph and telephone, and the rapid
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Chapter 1
demand for more capacity, led to the need for multiplexing more than one channel onto a single pair of copper conductors. While time division multiplexing (TDM) achieved some measure of popularity, frequency
division multiplexing (FDM) using various carrier-based systems was by far the most successful and widely
used. It was pulse code modulation (PCM), however, that put data converters on the map, and understanding its evolution is where we begin.
The material in the following sections has been extracted from a number of sources, but K. W. Cattermole’s
classic 1969 book, Principles of Pulse Code Modulation (Reference 3), is by far the most outstanding
source of historical material for both PCM and data converters. In addition to the historical material, the
book has excellent tutorials on sampling theory, data converter architectures, and many other topics relating to the subject. An extensive bibliography cites the important publications and patents behind the major
developments. In addition to Cattermole’s book, the reader is also referred to an excellent series of books
published by the Bell System under the title of A History of Engineering and Science in the Bell System
(References 4 through 8). These Bell System books are also excellent sources for background material on
the entire field of communications.

The Early Years: Telegraph to Telephone
According to Cattermole (Reference 3), the earliest proposals for the electric telegraph date from about
1753, but most actual development occurred from about 1825–1875. Various ideas for binary and ternary
numbers, codes of length varying inversely with probability of occurrence (Schilling, 1825), reflectedbinary (Elisha Gray, 1878—now referred to as the Gray code), and chain codes (Baudot, 1882) were
explored. With the expansion of telegraphy came the need for more capacity, and multiplexing more than
one signal on a single pair of conductors. Figure 1.2 shows a typical telegraph key and some highlights of
telegraph history.
•
•
•
•

Telegraph proposals: Started 1753
Major telegraph development: 1825−1875

Various binary codes developed
Experiments in multiplexing for increased channel
capacity

•

Telephone invented: 1875 by A. G. Bell while
working on a telegraph multiplexing project

•

Evolution:
− Telegraph: Digital
− Telephone: Analog
− Frequency division multiplexing (FDM): Analog
− Pulse code modulation (PCM): Back to Digital

Figure 1.2: The Telegraph

The invention of the telephone in 1875 by Alexander Graham Bell (References 9 and 10) was probably the
most significant event in the entire history of communications. It is interesting to note, however, that Bell
was actually experimenting with a telegraph multiplexing system (Bell called it the harmonic telegraph)
when he recognized the possibility of transmitting the voice itself as an analog signal.

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Data Converter History
Figure 1.3 shows a diagram from Bell’s original patent which puts forth his basic proposal

for the telephone. Sound vibrations applied
to the transmitter A cause the membrane a to
vibrate. The vibration of a causes a vibration
in the armature c which induces a current in
the wire e via the electromagnet b. The current
in e produces a corresponding fluctuation in
the magnetic field of electromagnet f, thereby
vibrating the receiver membrane i.
The proliferation of the telephone generated
a huge need to increase channel capacity by
Extracted from U.S. Patent 174,465,
multiplexing. It is interesting to note that
Filed February 14, 1876, Issued March 7, 1876
studies of multiplexing with respect to telegFigure 1.3: The Telephone
raphy led to the beginnings of information
theory. Time division multiplexing (TDM) for
telegraph was conceived as early as 1853 by a little known American inventor, M. B. Farmer; and J. M. E.
Baudot put it into practice in 1875 using rotating mechanical commutators as multiplexers.
In a 1903 patent (Reference 11), Willard M. Miner describes experiments using this type of electromechanical rotating commutator to multiplex several analog telephone conversations onto a single pair of wires as
shown in Figure 1.4. Quoting from his patent, he determined that each channel must be sampled at
“… a frequency or rapidity approximating the frequency or average frequency of the finer or
more complex vibrations which are characteristic of the voice or of articulate speech, …, as high
as 4320 closures per second, at which rate I find that the voice with all its original timbre and
individuality may be successfully reproduced in the receiving instrument. … I have also succeeded
in getting what might be considered as commercial results by using rates of closure that, comparatively speaking, are as low as 3500 closures per second, this being practically the rate of the
highest note which characterizes vowel sounds.”
At higher sampling rates, Miner found no
perceptible improvement in speech quality,
probably because of other artifacts and errors
in his rather crude system.

There was no follow-up to Miner’s work on
sampling and TDM, probably because there
were no adequate electrical components
available to make it practical. FDM was well
established by the time adequate components
did arrive.
Extracted from: Williard M. Miner, “Multiplex Telephony,” U.S. Patent 745,734,
Filed February 26, 1903, Issued December 1, 1903

Figure 1.4: One of the Earliest References to a
Criteria for Determining the Sampling Rate

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