®

REF200

7

100µA/200µA

4

5

3

In

Out

Com

Mirror

S

Compliance to –V + 1.5V

+V

S

100µA

100µA

S

–V

FIGURE 6. Improved Low-Voltage Compliance.

FIGURE 7. 100

µA Current Source—80V Compliance.

100µA

100µA

±

±

40k

Ω

40k

Ω

0.01µF

0.01µF

1N4148

1N4148

1N4148

1N4148

(e) Bidirectional 200µA

cascoded current source.

100µA

100µA

40k

Ω

40k

Ω

0.01µF

0.01µF

(d) Floating 200µA cascoded

current source.

100µA

L

o

a

d

–V

S

+V

S

(a) Compliance approximate

to Gnd. HV compliance

limited by FET breakdown.

100µA

L

o

a

d

+V

S

(b) Compliance to +V – 5V.

High

Low

100µA

–V

S

33k

Ω

0.01µF

S

100µA

L

o

a

d

+V

S

(c)

–V

S

27k

Ω

5.1V

1N4689

NOTES: (1) FET cascoded current sources offer improved output impedance and high frequency operation. Circuit in (b)

also provides improved PSRR. (2) For current sinks (Circuits (a) and (b) only), invert circuits and use “N” channel JFETS.

FIGURE 8. FET Cascode Circuits.

101

100

99

0

10

2030

40

50

607080

Applied Voltage (V)

Provides 2X Higher Compliance Voltage

SERIES-CONNECTED CURRENT SOURCES

CURRENT vs APPLIED VOLTAGE

100µA

100µA

High

Low