Question

Let the drain current of all FETs in active loaded MOS differential pair is 1 mA. Let VOV1 = 1V, VOV2 = 1.5V, VOV3 = 2.5V and VOV4 = 2V. Find the trans-conductance of the amplifier.

Answer 1

Let the drain current of all FETs in active loaded MOS differential pair is 1 mA. Let VOV1 = 1V, VOV2 = 1.5V, VOV3 = 2.5V and VOV4 = 2V. Find the trans-conductance of the amplifier.
As per the question, we need to calculate the trans-conductance of an active loaded MOS differential amplifier. Where, the voltage across the FETs are VOV1 = 1V, VOV2 = 1.5V, VOV3 = 2.5V and VOV4 = 2V, and the drain current of all the FETs is 1 mA. Therefore, the resultant trans-conductance can be calculated as
gm = gm1 + gm2 + gm3 + gm4 = Id/ VOV1 + Id/ VOV2 + Id/ VOV3 + Id/ VOV4
Inserting the values, we obtain
gm = 2.56 mA/V.