Week 6 Flashcards
How is a field effect transistor constructed?
An FET (field effect transistor) is constructed by placing an insulating layer on top of a silicon wafer
What are the two types of FETs?
n-channel and p-channel
True or False: FETs are symmetric devices
True
What are the names of the three terminals on an FET?
Drain, gate, and source
Define metal-oxide-semiconductor FET (MOSFET)
A MOSFET uses a metal plate at the gate to generate an electric field across an insulating layer (oxide) into the semiconductor substrate. This electric field helps (or hinders) the flow of current
Define enhancement-type MOSFET
A MOSFET that uses the generated electric field to increase current flow (or “turn on”)
Define depletion-type MOSFET
A MOSFET that uses the generated electric field to decrease current flow (or “turn off”)
Define a junction FET (JFET)
A JFET uses a reverse-biased pn-junction at the gate to create a depletion region between the source and the drain. This depletion region helps (or hinders) the flow of current
True or False: JFETs are enhancement-type FETs
False, the gate in a JFET is used to “turn off” the device
True or False: You can mess up a JFET circuit by accidentally forward-biasing the gate pn-junction
True
True or False: A FET has various modes of operation depending on the voltages at its terminals
True
True or False: A MOSFET is in saturation region when The drain-source voltage is just below the overdrive voltage
False, it’s in saturation when the drain-source voltage is above the overdrive voltage
Define overdrive voltage
The gate-source voltage minus the threshold voltage
True or False: A MOSFET has zero gate current
True
True or False: A MOSFET in the triode region often dissipates significantly higher power than in the saturation region
False, other way around is True
True or False: A MOSFET in triode region acts like a gate-controlled variable resistor
True
True or False: A transistor can be used as an amplifier
True
What order (highest to lowest) would the following circuit elements rank in terms of amplifier gain? BJT, JFET, or a MOSFET
BJT, JFET, MOSFET
What order (largest to smallest) would the following circuit elements rank in terms of amplifier frequency range? BJT, JFET, or a MOSFET
BJT, JFET, MOSFET
What order (largest to smallest) would the following circuit elements rank in terms of leakage current (base-gate current)? BJT, JFET, or a MOSFET
BJT, JFET, MOSFET
What order (fastest to sowest) would the following circuit elements rank in terms of switching speed? BJT, JFET, or a MOSFET
BJT & JFET (tied), MOSFET
What order (highest to lowest) would the following circuit elements rank in terms of heat tolerance? BJT, JFET, or a MOSFET
MOSFET, JFET & BJT (tied)
