LT1124/LT1125
applicaTions inForMaTion
The LT1124 may be inserted directly into OP-270 sock-
ets. The LT1125 plugs into OP-470 sockets. Of course,
all standard dual and quad bipolar op amps can also be
replaced by these devices.
(5µV/V). However, Table 1 can be used to estimate the
expected matching performance between the two sides of
the LT1124, and between amplifiers A and D, and between
amplifiers B and C of the LT1125.
Matching Specifications
Offset Voltage and Drift
Inmanyapplicationstheperformanceofasystemdepends
on the matching between two op amps, rather than the
individual characteristics of the two devices. The three op
ampinstrumentationamplifierconfigurationshowninthis
data sheet is an example. Matching characteristics are not
100% tested on the LT1124/LT1125.
Thermocouple effects, caused by temperature gradients
across dissimilar metals at the contacts to the input termi-
nals, can exceed the inherent drift of the amplifier unless
propercareisexercised.Aircurrentsshouldbeminimized,
package leads should be short, the two input leads should
beclosetogetherandmaintainedatthesametemperature.
Some specifications are guaranteed by definition. For
example, 70µV maximum offset voltage implies that mis-
match cannot be more than 140µV. 112dB (= 2.5µV/V)
CMRR means that worst-case CMRR match is 106dB
The circuit shown in Figure 1 to measure offset voltage
is also used as the burn-in configuration for the LT1124/
LT1125, with the supply voltages increased to 16V.
50k*
15V
–
+
100Ω*
50k*
V
OUT
–15V
V
= 1000V
OS
OUT
*RESISTORS MUST HAVE LOW
THERMOELECTRIC POTENTIAL
1124/25 F01
Figure 1. Test Circuit for Offset Voltage and
Offset Voltage Drift with Temperature
Table 1. Expected Match
PARAMETER
LT1124AC/AM
LT1125AC/AM
LT1124C/M
LT1125C/M
50% YIELD
98% YIELD
110
50% YIELD
98% YIELD
130
UNITS
µV
V
Match, ∆V
LT1124
LT1125
20
30
30
50
0.5
7
OS
OS
150
180
µV
Temperature Coefficient Match
Average Noninverting I
0.35
6
1.0
1.5
µV/°C
nA
18
25
B
Match of Noninverting I
CMRR Match
7
22
8
30
nA
B
126
127
115
123
127
112
dB
PSRR Match
118
114
dB
11245ff
10
For more information www.linear.com/LT1124
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