Question

Given a MOSFET where gate to source capacitance is 300 pF and gate to drain capacitance is 500 pF. Calculate the gain bandwidth product if the transconductance is 30 mΩ^-1.

(a) 5.98 Mhz

(b) 4.9 Mhz

(c) 6.5Mhz

(d) 5.22Mhz

The question was asked in an international level competition.

Question is taken from High Frequency Response topic in section Transistor Frequency Response of Analog Circuits

Answer 1

Correct answer is (a) 5.98 Mhz

To elaborate: Gain bandwidth product for any MOSFET is fT = gm/2π(Cgs+Cgd)

Thus GBP is approximately 5.9 Mhz.