2. amps-preamps
  3. 1114722232

Are MOSFET's voltage, not current, devices?

In reading the specs of a very well known line of amps that use MOSFET output transistors, I noticed that they have surprisingly low maximum output current.

I know that MOSFET's are said to mimic the operation of a vacuum tube (hence, the more tubey sound as compared to bipolar transistors). Is it also the case that, like tubes, they produce primarily voltage and not current?

Thanks in advance for your responses.
raquel

Showing 1 response by cford

cford
66 posts
 
Mosfets are voltage controlled devices, that is the more voltage on the gate the more fully they turn on and once turned on, they act like a resistor. The only current required to control them is to charge up any gate capacitance.
Bipolar transistors are current controlled devices, that is the more current flowing into the base, the more current can flow thru them. The only voltage required to turn them on is to overcome the voltage drop from base to emitter. Once fully turned on they have a fairly constant voltage drop, unlike a mosfet whos voltage drop = current x on resistance.
More to discover