A voltage amplifier is constructed using enhancement mode MOSFETs labelled M1, M2, M3 and M4 in the figure below. M1, M2 and M4 are n-channel MOSFETs and M3 is a p-channel MOSFET. All MOSFETs operate in saturation mode and channel length modulation can be ignored. The low frequency, small signal input and output voltages are vin and vout respectively and the dc power supply voltage is VDD. All n-channel MOSFETs have identical transconductance gmn while the p-channel MOSFET has transconductance gmp. The expressions for the low frequency small signal voltage gain Vout/Vin is

A voltage amplifier is constructed using enhancement mode MOSFETs labe

1.	A voltage amplifier is constructed using enhancement mode MOSFETs labelled M1, M2, M3 and M4 in the figure below. M1, M2 and M4 are n-channel MOSFETs and M3 is a p-channel MOSFET. All MOSFETs operate in saturation mode and channel length modulation can be ignored. The low frequency, small signal input and output voltages are vin and vout respectively and the dc power supply voltage is VDD. All n-channel MOSFETs have identical transconductance gmn while the p-channel MOSFET has transconductance gmp. The expressions for the low frequency small signal voltage gain Vout/Vin is
A.	−gmn/gmp
B.	−gmn (gmn + gmp)−1
C.	+gmn/gmp
D.	gmn (gmn + gmp)−1
Answer» D. gmn (gmn + gmp)−1