Current Sources and Voltage References

The JFET-DMOS cascode current source

Creating Medium-Power Current Sources with DMOS FETs

199

development it could be substituted by a good-quality multiturn trimmer potentiometer.

This would allow easy adjustment of the desired current level, which could range from

a few milliamps to a few tens of milliamps. It can be used equally well in circuits of

more than 200 volts or below 10 volts, depending on one’s choice of V

GS (off)

and other

device specifications. In the cascode shown, it provides an internal circuit impedance

of more than 10 MΩ at a current level of 10 mA. Capacitor C

1

is included for circuit sta-

bility, but its voltage rating should be ...