A MOSFET differential amplifier such as that shown in Fig. 10.34(a) is biased with a current source I = 400 μA.
The transistors have W/L = 16, k1n = 400 μA/V2,VA = 20 V, Cgs = 40 fF, Cgd = 5 fF, and Cdb = 5 fF. The drain resistors are 10 kΩ each. Also, there is a 100-fF capacitive load between each drain and ground. Find VOV and gm for each transistor.
(a) If the input signal source has a small resistance Rsig and thus the frequency response is determined primarily by
the output pole, estimate the 3-dB frequency fH.
(b) If, in a different situation, the amplifier is fed symmetrically with a signal source of 40 kΩ resistance (i.e., 20 kΩ in series with each gate terminal), use the open-circuit time-constants method to estimate fH.
