Electrical Engineering Stack Exchange is a question and answer site for electronics and electrical engineering professionals, students, and enthusiasts. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I have heard that mosfets can be converted into resistors if they are "depleted". Can somebody explain how this is done as simply as possible...I don't have an EE background.


share|improve this question

MOSFETs are resistors. By how much the channel conducts current is determined by construction of the MOSFET and the voltage on the gate. A depletion type MOSFET will conduct with no voltage applied to the gate, and require a voltage to increase the channel's resistance, while for an enhancement type it's just the other way around.

share|improve this answer

Depletion-mode MOSFETs are devices that will provide a voltage drop when current is drawn through them. They can be used in places where something like a pull-up resistor would be required, but they don't act like a typical resistor. A typical resistor will, throughout its useful operating range, drop a voltage proportional to current. A 10Kohm resistor will drop ten volts per milliamp, or ten millivolts per microamp. By contrast, a depletion-mode MOSFET might drop one volt at 100uA, but drop 0.5 volts at 75uA, or 3 volts at 120uA.

share|improve this answer

A voltage applied to the gate will reduce the width of source-drain channel. Less width/space to flow means less current. That's same as the function of a resistor. Its simple as that.

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.