LTC6943

10

6943f

Voltage Controlled Current Source with Ground Referred Input and Output

6943 • TA11

7

12

1µF

100Ω

100Ω

INPUT

0V TO 2V

1/2 LTC6943

11

14

10

9

6

1k

4

1

8

5V

2

3

1µF

0.001µF

OPERATES FROM A SINGLE 5V SUPPLY

0.68µF

5V

3

–

+

15

1/2 LT1013

TYPICAL APPLICATIO S

Lock-In Amplifier (= Extremely Narrow-Band Amplifier)

6943 • TA13

11

1/4 LTC6943

T1 = TF5SX17ZZ, TOROTEL

≈ 6.19k AT 37.5°C

MATCH 0.05%

6.19k = VISHAY S-102

OPERATE LTC6943 WITH

±5V SUPPLIES

LOCK-IN AMPLIFIER TECHNIQUE

USED TO EXTRACT VERY SMALL

SIGNALS BURIED INTO NOISE

5V

–5V

2

6.19k

100k

10k*

10k*

100Ω

0.01µF47µF

6.19k

1

4

3

6.19k

T1

500Hz

SINE DRIVE

THERMISTOR BRIDGE

IS THE SIGNAL SOURCE

SYNCHRONOUS

DEMODULATOR

RT

3

6

–

+

LT1007

5V

5V

–5V

ZERO CROSSING DETECTOR

2

3

4

1

8

1k

0.002

PHASE TRIM

50k

10k

7

5V

–5V

3

2

1M

1µF

–

+

LT1056

5V

–5V

2

3

4

6

–

+

LT1012

BRIDGE SIGNAL

10

12

14

–

+

LT1011

*

+