Datasheet

13
LT1078/LT1079
TYPICAL APPLICATIONS
U
Micropower, 10ppm/°C, ±5V Reference Gain of 10 Difference Amplifier
–
+
+
–
2M
220k
120k
3
2
1
8
4
1/2 LT1078
9V
5.000V
OUT
1M
6
5
7
LT1034BC-1.2
510k
1M
–5.000V
OUT
–9V
510k
1%
20k
160k
1%
1/2 LT1078
SUPPLY CURRENT = 9V BATTERY = 115µA
 –9V BATTERY = 85 µA
OUTPUT NOISE = 36µV
P-P
, 0.1Hz TO 10Hz
THE LT1078 CONTRIBUTES LESS THAN 3% OF THE TOTAL OUTPUT NOISE AND 
DRIFT WITH TIME AND TEMPERATURE. THE ACCURACY OF THE –5V OUTPUT
DEPENDS ON THE MATCHING OF THE TWO 1M RESISTORS
LT1078/79 • TA03
+
–
1M
1M
10M
OUTPUT
0.0035V TO 2.4V
1/2 LT1078
 BANDWIDTH= 20kHz
OUTPUT OFFSET= 0.7mV
 OUTPUT NOISE= 80 µV
P-P
(0.1Hz TO 10Hz)
 260 µV
RMS
OVER FULL 
 BANDWIDTH
THE USEFULNESS OF DIFFERENCE AMPLIFIERS IS LIMITED BY 
THE FACT THAT THE INPUT RESISTANCE IS EQUAL TO THE SOURCE
RESISTANCE. THE PICOAMPERE OFFSET CURRENT AND LOW 
CURRENT NOISE OF THE LT1078 ALLOWS THE USE OF 1M SOURCE
RESISTORS WITHOUT DEGRADATION IN PERFORMANCE. IN ADDITION,
WITH MEGOHM RESISTORS MICROPOWER OPERATION CAN BE MAINTAINED
LT1078/79 • TA04
–IN
+IN
10M
3V
Picoampere Input Current, Triple Op Amp Instrumentation Amplifier with Bias Current Cancellation
+
–
9
10
8
1/4 LT1079
–
+
+
–
–
+
R2
1M
R2
1M
1/4 LT1079
1/4 LT1079
1/4 LT1079
3
2
1
R1
1M
R1
1M
R
G

200k
6
5
7
12
13
14
R3
9.1M
R3
9.1M
9V
4
11
2R
20M
OUTPUT
4mV TO 8.2V
R
10M
2R
20M
–IN
+IN
GAIN = 1 +
()
2R1
R
G
R3
R2
= 100 FOR VALUES SHOWN
LT`1078/79 • TA05
INPUT BIAS CURRENT TYPICALLY < 150pA
INPUT RESISTANCE = 3R = 30M FOR VALUES SHOWN
NEGATIVE COMMON MODE LIMIT = (I
B
)(2R) + 20mV ≈ 140mV
GAIN BANDWIDTH PRODUCT = 1.8MHz