Comparison of BJT and FET
Parameter
|
BJT
|
FET
|
Control parameter
|
Current control device
|
Voltage control device
|
Input junction
|
Always forward biased
|
Always reversed biased
|
charge carriers
|
Electrons and holes both are carrying current
|
Either electrons or holes carry currents.
|
Noise
|
More noise
|
less noise
|
Terminals
|
Emitter, base collector
|
Source, Gate Drain
|
FET
|
BJT
|
It is unipolar device i.e. current in the device is carried either by electrons or holes
|
It is bipolar device i.e. current in the device is carried either by both electrons & holes
|
It is a voltage controlled device i.e. voltage at the gate (or drain) terminal controls amount of current flowing through the device.
|
It is a current controlled device i.e. the base current controls the amount of collector current.
|
It has a negative temperature coefficient at high current levels. It means that current decreases as temperature increases.
|
It has a positive temperature coefficient at high current levels. It means that current increases as temperature increases.
|
It has relatively lower gain bandwidth product as compared to BJT.
|
It has relatively higher gain bandwidth product as compared to FET.
|
It is less noisy.
|
It is comparatively more noisy.
|
It is relatively immune to radiation.
|
It is susceptible to radiation
|