AN-24 Datasheet, PDF (1/10 Pages) List of Unclassifed Manufacturers – A Simplified Test Set for Op Amp Characterization

A Simplified Test Set for Op
National Semiconductor
Application Note 24
Amp Characterization
M Yamatake
April 1986
INTRODUCTION
The test set described in this paper allows complete quanti-
tative characterization of all dc operational amplifier param-
eters quickly and with a minimum of additional equipment
The method used is accurate and is equally suitable for lab-
oratory or production test for quantitative readout or for
limit testing As embodied here the test set is conditioned
for testing the LM709 and LM101 amplifiers however sim-
ple changes discussed in the text will allow testing of any of
the generally available operational amplifiers
Amplifier parameters are tested over the full range of com-
mon mode and power supply voltages with either of two
output loads Test set sensitivity and stability are adequate
for testing all presently available integrated amplifiers
The paper will be divided into two sections i e a functional
description and a discussion of circuit operation Complete
construction information will be given including a layout for
the tester circuit boards
FUNCTIONAL DESCRIPTION
The test set operates in one of three basic modes These
are (1) Bias Current Test (2) Offset Voltage Offset Current
Test and (3) Transfer Function Test In the first two of these
tests the amplifier under test is exercised throughout its full
common mode range In all three tests power supply volt-
ages for the circuit under test may be set at g5V g10V
g15V or g20V
POWER SUPPLY
Basic waveforms and dc operating voltages for the test set
are derived from a power supply section comprising a posi-
tive and a negative rectifier and filter a test set voltage
regulator a test circuit voltage regulator and a function gen-
erator The dc supplies will be discussed in the section deal-
ing with detailed circuit description
The waveform generator provides three output functions a
g19V square wave a b19V to a19V pulse with a 1% duty
cycle and a g5V triangular wave The square wave is the
basic waveform from which both the pulse and triangular
wave outputs are derived
The square wave generator is an operational amplifier con-
nected as an astable multivibrator This amplifier provides
an output of approximately g19V at 16 Hz This square
wave is used to drive junction FET switches in the test set
and to generate the pulse and triangular waveforms
The pulse generator is a monostable multivibrator driven by
the output of the square wave generator This multivibrator
is allowed to swing from negative saturation to positive satu-
ration on the positive going edge of the square wave input
and has a time constant which will provide a duty cycle of
approximately 1% The output is approximately b19V to
a19V
FIGURE 1 Functional Diagram of Bias Current Test Circuit
TL H 7190 – 1
C1995 National Semiconductor Corporation TL H 7190
RRD-B30M115 Printed in U S A