LT1012_15 Datasheet, PDF (12/20 Pages) Linear Technology – Picoamp Input Current, Microvolt Offset, Low Noise Op Amp

LT1012A/LT1012
APPLICATIO S I FOR ATIO
Test Circuit for Offset Voltage
and its Drift with Temperature
50k *
15V
2_– ⁷
100Ω*
6
LT1012
V₀
3₊
4
50k*
–15V
V₀ = 1000V_0S
*RESISTORS MUST HAVE LOW THERMOELECTRIC
POTENTIAL
LT1012A • AI02
Follower Feedforward Compensation
50pF
5k
IN
10k
2_–
6
LT1012
OUT
3₊
5
0.01µF
LT1012A • AI03
Pulse Response of Feedforward
Compensation
Photoo
5µs/DIV
TYPICAL APPLICATIO S
Ampmeter with Six Decade Range
10k
CURRENT INPUT
0.1µF
15V
10k _{2 –}
7
LT1012
3₊
4
–15V
Q1, Q2, Q3, Q4, RCA CA3146 TRANSISTOR ARRAY.
CALIBRATION: ADJUST R1 FOR FULL-SCALE
DEFLECTION WITH 1µA INPUT CURRENT
AMPMETER MEASURES CURRENTS FROM 100pA
TO 100µA WITHOUT THE USE OF EXPENSIVE
HIGH VALUE RESISTORS. ACCURACY AT 100µA
IS LIMITED BY THE OFFSET VOLTAGE BETWEEN
Q1 AND Q2 AND, AT 100pA, BY THE INVERTING
BIAS CURRENT OF THE LT1012
Q3
6
33k
PIN 13
CA3146
100µA
METER
100pA
RANGE
Q1 Q2
1nA
10nA
100nA
Q4
1µA
10µA
100µA
R1
2k
1.2k
549Ω
549Ω
549Ω
549Ω
549Ω
549Ω
12
10k
15V
LT1004C
LT1012A • TA03
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