FET Fundamentals Unit 2 – Junction FETS
Exercise 1 – JFET Operating Characteristics
EXERCISE OBJECTIVE
When you have completed this exercise, you will be able to describe the drain current
characteristics of a junction field-effect transistor (JFET). You will verify your results with a
multimeter and an oscilloscope.
DISCUSSION
- Drain current (ID) is maximum when the transistor is zero biased. Maximum drain current is
symbolized as IDSS. - Drain current is varied by changing the value of the drain to source voltage (VDS).
- Increasing VDS past saturation produces avalanche breakdown.
- Gate to source voltage (VGS) is negative to correctly bias a N-channel JFET.