LT1127CS 查看數據表（PDF） - Linear Technology
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LT1127CS Datasheet PDF : 8 Pages
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LT1126/LT1127
APPLICATI S I FOR ATIO
Matching Specifications
High Speed Operation
In many applications the performance of a system de-
pends on the matching between two op amps, rather than
the individual characteristics of the two devices. The three
op amp instrumentation amplifier configuration shown in
this data sheet is an example. Matching characteristics are
not 100% tested on the LT1126/LT1127.
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
(5µV/V). However, the following table can be used to
estimate the expected matching performance between the
two sides of the LT1126, and between amplifiers A and D,
and between amplifiers B and C of the LT1127.
When the feedback around the op amp is resistive (RF), a
pole will be created with RF, the source resistance and
capacitance (RS, CS), and the amplifier input capacitance
(CIN ≈ 2pF). In low closed loop gain configurations and
with RS and RF in the kilohm range, this pole can create
excess phase shift and even oscillation. A small capacitor
(CF) in parallel with RF eliminates this problem. With
RS (CS + CIN) = RF CF, the effect of the feedback pole is
completely removed.
CF
RF
–
CIN
RS
CS
+
OUTPUT
LT1126 • TA02
Expected Match
PARAMETER
VOS Match, ∆VOS LT1126
LT1127
Temperature Coefficient Match
Average Non-Inverting IB
Match of Non-Inverting IB
CMRR Match
PSRR Match
LT1126AM/AC
LT1127AM/AC
50% YIELD
98% YIELD
20
110
30
150
0.35
1.0
6
18
7
22
126
115
127
118
LT1126M/C
LT1127M/C
50% YIELD
98% YIELD
30
130
50
180
0.5
1.5
7
25
8
30
123
112
127
114
UNITS
µV
µV
µV/°C
nA
nA
dB
dB
TYPICAL APPLICATI S
Gain 1000 Amplifier with 0.01% Accuracy, DC to 5Hz
340k 15k 20k
1% 5% TRIM
365Ω
1%
+15V
–
INPUT
LT1126
+
–15V
OUTPUT
RN60C FILM RESISTORS
THE HIGH GAIN AND WIDE BANDWIDTH OF THE LT1126/LT1127 IS USEFUL IN LOW FREQUENCY HIGH CLOSED
LOOP GAIN AMPLIFIER APPLICATIONS. A TYPICAL PRECISION OP AMP MAY HAVE AN OPEN LOOP GAIN OF ONE
MILLION WITH 500kHz BANDWIDTH. AS THE GAIN ERROR PLOT SHOWS, THIS DEVICE IS CAPABLE OF 0.1%
AMPLIFYING ACCURACY UP TO 0.3Hz ONLY. EVEN INSTRUMENTATION RANGE SIGNALS CAN VARY AT A FASTER
RATE. THE LT1126/LT1127 “GAIN PRECISION — BANDWIDTH PRODUCT” IS 330 TIMES HIGHER, AS SHOWN.
LT1126 • TA03
6
Gain Error vs Frequency
Closed Loop Gain = 1000
1.0
TYPICAL
PRECISION
OP AMP
0.1
0.01
LT1126/LT1127
0.001
0.1
GAIN
ERROR
=
CLOSED LOOP GAIN
OPEN LOOP GAIN
1
10
100
FREQUENCY (Hz)
LT1126 • TA04
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