FET Fundamentals Unit 5 – Dual Gate MOSFET
Exercise 1 – MOSFET Modes Of Operation
EXERCISE OBJECTIVE
When you have completed this exercise, you will be able to determine the effect of bias on the
operating modes of the MOSFET by using a typical test circuit. You will verify your results with
a multimeter and an oscilloscope.
DISCUSSION
- The MOSFET used in this unit is a dual gate N-channel depletion mode MOSFET which can
operate in either depletion or enhancement mode. - Both gates can be connected and operated as a single gate device.
- Most MOSFET’s have internal diodes that protect the gate static electric discharge. These
diodes are called internal gate protection diodes and are not shown as part of the MOSFET
schematic symbol. - In depletion mode, the N-channel MOSFET has a negative bias applied to the gate with
respect to the source. - In enhancement mode, the N-channel MOSFET has a positive bias voltage applied to the
gate with respect to the source.