The Best of Analog Dialogue
A Brief History  President's Message  Preface and Introduction  Table of Contents  Subject Index
Subject Index


A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z  
A  
Addressing, data, DSP  200 
AGC, see Automatic gain control  
ALU, see Arithmetic and logic unit  
Amplifier, audio, op amp as  180 
Amplifier, difference, grounding with  86 
Amplifier, instrumentation  59 
offset, referred to input (RTI) and output (TRO)  59 
Amplifier, isolation  110 
as coupling  50 
applications:  
electronic instrumentation  115 
noise & vibration measurement  111 
temperature measurement  111 
circuit practice  50 
guidelines  50 
highlinearity  110 
Model 289  110 
applications  111 
principle  110 
synchronizable  110 
threeport  110 
wideband  110 
shielding & guarding  50 
Amplifier, logarithmic, wideband, AD640  189 
analysis, simplified  191 
biasing accuracy in  192 
block diagram  190 
implementation  191 
temperature stabilization  192 
theory  190 
Amplifier, operational (op amp)  9, 19, 32, 48, 66, 151, 177, 185, 202 
as electrometer  48 
as integrator  3 
commonmode rejection (CMR)  15, 16 
complementary bipolar (CB) process AD840 series  177 
applications  179 
comparative specifications  177 
JFET input (AD845)  178 
speed and accuracy  177 
testing  179 
transimpedance (AD846)  178 
wideband, highslewrate (AD847)  179 
wideband, fastsettling (AD840/41/42)  178 
current, bias  13, 14 
current, difference, initial—and test  13, 14 
decoupling  194 
dielectric absorption in circuits  35 
distortion  11 
drift  13 
with time  14 
equivalent circuit  9 
femtoampere (10^{15} A) measurements with  48 
gain test  10 
high speed  66 
choosing  67 
impedance, input  14 
test circuits  15 
inputs, guarding  148 
loop gain  10 
measurements, bandwidth and slew rate  11 
noise  19, 151, 202 
calculations  155 
curves  29 
gain  21 
input  16 
model  20 
response, dynamic  156 
source impedance  203 
spectral density  29 
testing  157 
openloop gain  9, 10 
overload recovery  12 
response  32, 66 
fullpower  11, 12 
unity gain  11 
settling time  32, 67 
and voltage swing  3638 
bibliography  42 
factors affecting  33, 34 
measuring  39, 40 
minimizing—suggestions  36, 68 
polezero mismatch  41 
specifications, limitations of  39 
specifying  36 
thermal effects  36 
signal gain  21 
slew rate  11, 12, 35, 66 
specifications  9 
supply voltage, sensitivity to  14 
tests (see also individual parameters)  10 
CMR  16 
fullpower response  12 
overload recovery  12 
slew rate  12 
voltage:  
between inputs, maximum  15 
commonmode, maximum  15 
offset, initial—and test  13, 14 
Amplifier trimming  185 
Amplifier, voltagecontrolled, AD534 multiplier as  77 
Antilogarithmic and logarithmic analog
computation, with AD538 y(z/x)^{m}, multifunction  164 
Antilogarithmic circuits, in multifunction module  55 
Approximating functions with DSP building blocks  160 
Arctangent computation with multifunction circuit  62 
Arithmetic and logic unit (ALU), floating point, ADSP3220  168 
Arithmetic functions in DSP  199 
Attenuation, digitally controlled, with DACs  92 
Audio measurements, dB and truerms  81 
Automatic gain control (AGC), levelindependent:  
as tracking ADC  130 
using LOGDAC™  130 
B  
Bangap principle  71 
Bandgap voltage reference  71 
Bandwidth, noise vs. signal  22 
Board, printedcircuit:  
ground circuits  195 
grounding  195 
layout problems, avoiding  195 
magnetic effects  195 
problems of, static and dynamic  147 
Bridge linearization, multiplier in (AD534)  78 
Bypassing  84 
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C  
Cable capacitance, in electrometer circuits  49 
Calibration  185 
Capacitances, system, typical  121 
Capacitor:  
dielectric absorption, see Dielectric absorption  
dissipation factor  7, 144 
in integrator circuit  6 
insulation resistance  6 
leakage  144 
performance table  6 
problems of (see also Dielectric absorption, dissipation factor, leakage):  
other effects  144 
parasitic effects  144 
problems in assembly  145 
temperature  144 
tolerance  144 
CEG/DAC™ antialiasing D/A converter for video graphics:  
algorithm  210 
color transition smoothing  210 
design  211 
example  212 
"jaggie" elimination  210 
principles  211 
Circuit practice (see also Practice),
interference reduction for video converters 
149 
Circuits, printed: rules  149 
CMOS (complementary metaloxide semiconductors) & static electricity 
69 
circuit protection  69, 70 
D/A converters, advantages  63 
SCR "latch" mechanism  69 
switches  116 
dielectrically isolated  116 
equivalent circuit  116 
in DACs (see also DACs and Converters, D/A)  64 
Codec (coderdecoder)  108 
Communications, serial  184 
sensor information  181 
Components, passive  143 
avoiding pitfalls  143 
bibliography  148 
Computation, algebraic  
converters in  94 
quotients  94 
Computation, analog (see also specific functions):  
converters in  94 
D% ratio, AD534 in  77 
Conditioning, signal  184 
with 6B Series  181 
Controller, current  96 
Conversion, frequencytovoltage with AD537  75 
Conversion, high speed, bibliography  109 
trouble—avoiding  109 
Conversion, temperaturetofrequency, V/f used in  7375 
Converter, analogtodigital (A/D, see also ADC)  45, 73, 97, 105, 118, 181, 196 
12bit, complete IC, AD574  97 
analog features  97 
digital controls  97 
multiplexing 8bit bus  99 
standalone conversion  99 
technology  100 
"flash"  107, 196 
10bit AD9020/60  197 
evaluation board  198 
interpolation in  196 
linearity improvement  198 
performance  198 
principles  198 
Gray code  106 
input loading, buffering (see also successive approximation)  87, 180 
noise effects in  204 
perchannel  4547 
ranging converter using multiplying DAC  92 
subranging conversion  107 
digitally corrected  108 
trimming  185 
successive approximation, input buffering  82, 87, 88, 180 
testing  118 
automatic  118 
linearity  119 
transition finding  118 
Converter applications, circuit ideas  94 
Converter, digitaltoanalog (D/A, DAC)  63, 82, 92, 94, 105, 130, 206, 209 
AD7520  63 
applications  65 
circuit ideas  94 
CMOS:  
advantages  63 
equivalent circuit  64 
variable output resistance effects  84 
zeroing problems  83 
current output, CMOS:  
application problems  82 
capacitive load  82, 83 
displays  210 
dither, in testing A/D converters  119 
glitches  33, 106 
monolithic  63 
multiplying  63 
application ideas for  92 
gain control in  92 
trimming  185 
Converter, frequencytovoltage (f/V)  
inverse VFC  188 
phaselocked loop  188 
synchronous  188 
Converter, high speed, applications, specs, testing  108 
Converter, ohmstofrequency  94 
Converter, resistancetofrequency  94 
Converter, temperaturetofrequency, with AD537 VFC  75 
Converter, voltagetofrequency (V/f, VFC)  73, 187 
AD537 IC  73 
applications  74,75 
as data encoder  75 
as f/V converter  75 
circuit ideas  94 
interfacing with resistive transducer  75 
performance  74 
principle  73 
single supply  73 
squarewave out  73 
twowire operation  75 
chargebalance type  187 
circuit precautions  188 
errors  187 
multivibrator type  187 
software calibration  187 
synchronous  188 
trimming gain  185 
trimming gain and offset  185, 187 
Converters, video (see also specific types)  105, 196, 209 
Convolution  135 
Cosine computation with multifunction circuit  62 
Crest factor (ratio of peak to rms)  22 
Current controller  96 
Currentloop output, 6B Series  181 
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D  
Data acquisition  45, 103, 105, 181, 196 
conventional  4547 
vs. converterperchannel  4547 
high speed  105 
practice  109 
video  105 
Decoupling  84, 87, 120 
ineffective  85 
op amps  193 
Delays, matching, measuring unknowns with AD9500  176 
Dielectric absorption (see also Capacitor)  7, 143 
and settling time  35 
in electrometer circuits  49 
in sampleholds  52 
Dielectric isolation  116 
Digital signal processor, singlechip (DSP)  171, 199 
architecture  171173 
arithmetic  172, 173, 199 
choice of  199 
data flow  173, 199 
instruction set  173, 199 
program sequencing  173, 199 
vs."CISC"  201 
vs. "RISC"  201 
arithmetic computations  171174, 199 
data addressing  172, 173, 200 
program sequencing  172, 173, 200 
Displays: "jaggies", eliminating using CEG/DAC™  209 
Divider (analog computing, see also multifunction)  55, 58 
AD534 analog multiplier, basic connections  76 
with AD538 y(z/x)^{m}, multifunction circuit  164 
errors  167 
Doubleprecision arithmetic  168 
Drift (see also Offset)  
integrator  3 
long term, vs. 1/f noise  205 
op amp, with temperature  13 
E  
Electrometer  48 
cable capacitance effects  49 
input current limits  49 
noise  49 
resistors for  48 
using op amps  48 
voltage drift  49 
A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z  
F  
Filter, analog vs digital  135 
Filter, digital  135, 171 
adaptive  136 
basics  135 
characteristics  
ease of design  136 
efficiency  137 
memory requirements  137 
phase response  136 
sensitivity to coefficient error  136 
stability  136 
design  135 
hardware  140 
Remez exchange algorithm  138 
roundoff error  141 
simulation in software  141 
multipliers in  135 
nonrecursive  135 
references  142 
terminology  142 
type:  
finite impulse response (FIR)  136 
infinite impulse response (IIR)  136 
lattice  136 
Filter, FIR (finite impulseresponse)  135, 136 
design  135 
windowing approach  137 
analog timedomain, digitally programmable  93 
Filter, lowpass, voltagecontrolled using AD534  79 
Filter, programmable digitally, using an MDAC  93 
Filter, time domain, digitally programmed (analog FIR)  93 
FIR, see Filters  135 
Floatingpoint arithmetic chips  168 
pipelined operation  170 
Floating point, IEEE754, single and double precision  169 
Fourier theorem in filter design  136 
Functions, approximation  60, 160 
analog, see Multifunction  
DSP in  160 
fast and simple  160 
NewtonRaphson  160 
errors  162 
implementation  161 
preparations  161 
simpler implementations  162, 163 
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G  
Gain:  
adjustment  63, 76, 92, 94, 130, 189, 206 
automatic, TrimDAC7™(DAC8840/41)  206, 207 
logarithmic, with LOGDAC™  130 
amplifier noise gain and signal gain  21 
calibration, digital  96 
digitally controlled  92 
programmable, for trimming  95 
trimming  185 
DACs in (see also Trim)  96 
Gaussian distribution, noise  151 
Glitch, in D/A converters  106 
Graphics, video, principles in brief  210 
Grounding, amplifier: differenceinput  86 
Grounding  82, 149, 193 
current path in  195 
highfrequency  193 
improper  85 
lowfrequency  193 
proper  85, 86 
Ground, opamp  193 
Guarding  124, 128 
opamp inputs  148 
vs. shielding  128 
H  
Highspeedandaccuracy signal handling  82 
Highspeed circuits, ground rules: layout & wiring  149 
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I  
IEEE754 floatingpoint standard, arithmetic chips for  168 
IIR filter (see also Filter)  136 
Instrumentation, electrical, isolation amplifiers in  111 
Integrationcomplementary monolithic processing  100 
Integrator, analog  3 
errors:  
bandwidth  4 
gain  4 
highfrequency  4 
impedance  4 
in hold  5 
low frequency  5 
due to finite gain  5 
feedback capacitors in  6 
for ac signals  7 
frequency response  8 
gain, openloop, effective  8 
leakage resistance  7 
test circuit  8 
Interference (see also Noise, interference)  120, 124 
minimizing  149 
proper techniques, diagrams  84 
understanding  120 
Isolation, dielectric, for CMOS switches  116 
Isolator (see also Amplifier, isolation)  
circuit practice  50 
threeport  110 
J  
K  
L  
Leakage, in capacitors  144 
Linearity, A/D converters, testing  119 
Linearizing:  
in 6B input/output signal conditioners  184 
RTD (resistance temperature detector)  184 
Logarithm and antilogarithm, analog computation using multifunction devices  55 
AD538 y(z/x)^{m} multifunction  164 
log ratio with  167 
LOGDAC™, MDAC with
linear analog response and exponential conversion gain  130 
AD711x  130 
AGC application  130 
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M  
MACBASIC, language for MACSYM II  104 
MACSYM II Measurement
And Control SYsteM, described, features, and software  103, 104 
MDAC (multiplying D/A converter, see also Converter)  93 
Meter, dB  81 
Meter, trueRMS  81 
Microprocessor, DSP, singlechip ADSP2100  171, 199 
Benchmarks  171 
computing with  172 
example of FIR filter design  174 
instruction set  173 
memory communications  172 
system development  173 
Modulator, amplitude, AD534 as  77 
Multifunction, analog computing
device, y(z/x)^{m},
(see also individual functions)  55, 60 164 
AD538 IC  164 
dividers compared,  57, 166 
division,  57, 166 
minimizes noise  58 
exponents, noninteger  61, 167 
logarithms  57, 167 
log of voltage ratio  58, 167 
model 433, module  5558, 59, 6062 
performance characteristics  57, 165167 
principles  55, 57, 165, 166 
rms computation  58 
rootsumofsquares computation  60 
square root computation  57 
trig functions  61, 62 
vector summation  58 
Multiplier, analog (see also Multifunction)  55, 60, 76, 164 
AD534 IC  76 
applications  7781 
as divider, basic connections  76 
as multiplier, basic connections  76 
AD538 y(z/x)^{m}, multifunction as multiplier  164 
lasertrimmed  76 
linearized transconductance  76 
multifunction circuit as  55, 164 
output as voltagetocurrent converter  77 
translinear  76 
Multiplier, digital  135, 160, 168, 171, 199 
floating point ADSP3210  168 
in filter design  135 
Multiplierdivider, analog (see also Multifunction)  55, 164 
AD538 y(z/x)^{m}, multifunction as  164 
applications  166 
characteristics  165 
how it works  165 
A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z  
N  
Noise (see also Noise, interference)  19, 120, 124, 151, 202 
1/f, (see also flicker)  24, 152 
and drift  205 
spectral density  25 
amplifier  151, 154 
current  27 
voltage  27 
bandwidth, vs. signal bandwidth  22 
bibliography  31, 157, 203 
capacitively coupled, dealing with  121, 124 
characterization of  22 
combining  154 
commonimpedance  121 
computation example  26, 27 
crest factor  22, 154 
current  20 
defined  19 
device (also inherent; intrinsic)  22, 120, 151, 202 
interference (also induced)  22, 120, 151, 202 
transmitted (arriving with the signal)  120, 151 
density spectrum  153 
equivalent resistance  155 
filter:  
brickwall  156 
skirts  25, 156 
flicker (see also 1/f)  23, 24, 154 
Gaussian distribution in  151, 203 
in devices  151 
induced  151 
in feedback circuits  21 
inherent  22 
Johnson  23, 152, 203 
low frequency, measurements  204 
magnetically coupled  122, 126, 127 
loop effects  128 
op amp  19 
calculations  155 
model  20 
random, sources  202 
peak values  22 
vs. rms  204 
popcorn  23, 24, 152, 204 
practical considerations  30 
quantitative measures  152 
random  152 
bibliography  157 
current  202 
measuring  151 
understanding  151 
why ÖHz?  202 
references, see bibliography  
relevant points  25 
resistors  27 
rms value  22 
measurement  80 
vs. peaktopeak  204 
rootsumofsquares (RSS) summation  21 
shot (or Schottky)  23, 24, 152 
applicability of formula  205 
source impedance  203 
spectral density  34 
examples  153 
"pink" noise  25 
plots  29 
spot noise  25, 153 
summation using pink noise tangent approach  26 
white noise  24 
testing  157 
thermal  23 
transmitted  151 
voltage  20 
white  152, 153 
why be concerned  151 
Noise & vibration measurement, w/ isolation amplifiers  111 
Noise figure  28, 155, 203 
Noise gain  204 
Noise, interference (see also Noise)  19, 22, 120, 124 
assumptions  120 
basic principle  120 
excluding  124 
highfrequency, grounding  195 
rational approaches  120 
reduction  120, 124 
bibliography  129 
decoupling  194 
grounding  193 
sources  23, 120, 124 
capacitively coupled  121 
commonimpedance  121 
coupling—capacitive vs. magnetic  122 
magnetically coupled  121 
miscellaneous sources  121 
possible solutions  123 
powerline transients  121, 122 
understanding  120 
vs. "internal"  202 
Noise power ratio (NPR)  108 
Nonlinear effects on amplifier settling time  35 
NPR, see Noise power ratio  
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O  
Offset:  
adjustment, automatic, using TrimDAC™  206 
input, trimming  186 
integrator  3 
output, trimming  186 
Op amp, see Amplifier, operational  
Oscillator:  
programmable, using AD9500 delay generator  176 
square wave, programmable, 8bit  95 
twophase, voltagecontrolled, using AD534  79 
Wienbridge, stabilized, using AD534  79 
P  
Potentiometers, problems of  147 
Powers & roots—analog
computation
using AD538 y(z/x)^{m}, multifunction  164 
Power supply interference, bypassing  82 
Power supply, linear vs switching  109 
Practice, circuit:  
bibliography  148 
general  149 
grounding  150 
high speed  109 
power supplies  150 
using ICs  150 
what to overlook (nothing!)  148 
Printedcircuit boards, problems of:  
dynamic  147 
rules  149 
static  147 
Processing, signal, digital, see DSP  171, 199 
PTAT (proportional to absolute temperature)  71, 89, 192 
Q  
A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z  
R  
R2R ladder, in DAC  64 
Reference, voltage  71 
AD580  71 
bandgap circuits  71, 72 
IC  71 
Zener  71 
synthetic  71 
Remez exchange algorithm in digital filter design  138 
Requesttosend (RTS), in serial communication with 6B Series  183 
Resistors  143 
electrometer applications  48 
problems of  145, 146 
aging  146 
excess noise  146 
failures  146 
parasitic effects  146 
selfheating  145 
temperature effects  145 
thermoelectric effects  146 
voltage effects  146 
variable, vs. TrimDAC™  208 
RMS, see Root meansquare  
Roots and powers in analog computations
using the AD538 y(z/x)^{m} multifunction device  164 
Root meansquare (RMS)  22, 78, 80, 81 
and peak  22 
decibel (dB) output  80, 81 
measurement  80 
multifunction device in  58 
wideband, highcrestfactor, with AD534  78 
todB meter  81 
todc converter, monolithic, AD536  80, 81 
applications  81 
principle  81 
vs. ac average  22 
Root sumofsquares (RSS)  21 
computation with multifunction circuit  60 
RTD (resistance temperature detector) to serial output, using 6B Series  181 
RTS (requesttosend) in serial communications with the 6B Series  183 
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S  
Samplehold (also trackhold)  51, 105 
applications  53, 54 
characteristics  51 
design examples  52, 53 
errors  51 
hold mode  
dielectric absorption  52 
droop  52 
feedthrough  52 
holdtosample  
acquisition time  52 
holdtosample transients  52 
sample mode  
nonlinearity  51 
sample mode offset  51 
sample mode scalefactor error  51 
sample mode settling time  52 
sampletohold  
aperture time  52 
sampletohold offset  52 
sampletohold settling time  52 
sampletohold switching transients  52 
uses  51 
Sensor:  
serial input/output (VO) using the 6B Series  181 
toserial with the 6B Series  182 
gain & rangmg  182 
gate array  182 
isolation  182 
microcontrol  182 
reference calibration  182 
serial commumcations  183 
temperature compensation  182 
Sequencing, program, in DSP  200 
Serial input/output, sensors for usmg the 6B Series  181 
Settling time  32 
bibliography  42 
definition  32, 33 
long tails  36 
measuring  39, 40 
minimizing in opamp circuit  36 
polezero mismatch effects  41 
sampleholds  52 
specifications, limitations of  39 
specifying  36 
"specsmanship"  33 
thermal effects  36 
Shield:  
driven  128 
electrostatic  124126 
proper connection  125 
mumetal  127 
Shielding  124 
attenuation, various materials  127 
considerations, compared  129 
effect vs. thickness  127 
shielding, twisted pairs  127 
vs. guarding  128 
Signals:  
analog to serial  183 
analog transmission using VFC  187 
handling for high speed and accuracy  82 
Sine:  
approximation using the AD534  78 
multifunctioncircuit approximation  61 
Square root, multiplier as, using the AD534  79 
Squares, difference of, using the AD534  78 
Switches, analog, CMOS  116 
dielectrically isolated  116 
equivalent circuit  116 
in DACs  64 
in op amp circuits  117 
R_{ON} vs V_{D}(V_{S})  117 
Systems, conversion, highspeed—practice  109 
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T  
Tan^{l}, using multifunction circuits  62 
Temperature measurement  89 
difference, using the AD590  91 
isolation amplifiers in  111 
multiplexing, with AD590 matrix  91 
Testing, automatic  115, 118 
A/D converters, using LTS2000 family  118 
linearity of A/D converters  119 
Test system, automatic, for components, LTS2000 family  115 
Thermocouple to serial digital output, using 6B Series  181 
Time delay, programmable, using the AD9500 IC  175 
applications  176 
how it works  175 
Time, settling, of op amps, see Settling time  
Trackhold, see also Samplehold  51 
Transducer, absolutetemperaturetocurrent, AD590, 1 µA/K  89 
accuracy  90 
applications  91 
ease of application  89 
principle  89, 90 
trimming  90 
Transients, power line  122 
Transitionfinding in automatic A/D converter testing  105 
TrimDAC™ vs. variable resistors  208 
Trimming, automatic, TrimDAC™  206 
Trimming: circuits, gain, and offsets  185, 186 
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U  
V  
VFC, see Converter, voltagetofrequency  
VGA graphics, improvement with CEG/DAC™  209 
Video converters  105 
Video line driver, op amp as  180 
Voltage offset, programmable  96 
W  
X  
Y  
Z 

A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z 