Which transistor has higher gain. BJT or MOS and why?
Which transistor has higher gain. BJT or MOS and why?
Which transistor has higher gain. BJT or MOS and why?
Re: Which transistor has higher gain. BJT or MOS and why?
BJT have more gain than MOSFET because MOSFET shows Quadratic I-V characteristics and BJT shows Exponential I-V characteristics and the change in exponential behavior is more as compared to Quadratic behavior.
In mathematical terms:
The Intrinsic Gain in BJT = Va/Vt
where Va is Early Voltage.
It is a process parameter and its value lies in between 35V to 130V. Vt is thermal voltage and its value is 0.025V at room temperature. So, its Intrinsic Gain ranges from 1000 V/V to 5000 V/V.
In MOSFET Intrinsic Gain is 2Va/(Vgs - Vth)
where Va is Early Voltage same as in BJT.
Vgs is Gate to Source Voltage
Vth is threshold voltage
(Vgs - Vth) is higher as compared to thermal voltage Vt.
Normally (Vgs - Vth) is considered in between (0.2 -0.4).
So, MOSFETs have lower intrinsic gain as compared to BJT.
In mathematical terms:
The Intrinsic Gain in BJT = Va/Vt
where Va is Early Voltage.
It is a process parameter and its value lies in between 35V to 130V. Vt is thermal voltage and its value is 0.025V at room temperature. So, its Intrinsic Gain ranges from 1000 V/V to 5000 V/V.
In MOSFET Intrinsic Gain is 2Va/(Vgs - Vth)
where Va is Early Voltage same as in BJT.
Vgs is Gate to Source Voltage
Vth is threshold voltage
(Vgs - Vth) is higher as compared to thermal voltage Vt.
Normally (Vgs - Vth) is considered in between (0.2 -0.4).
So, MOSFETs have lower intrinsic gain as compared to BJT.
Re: Which transistor has higher gain. BJT or MOS and why?
The transconductance of BJT is higher than that of MOSFET which makes the gain of BJT higher than MOSFET.