**9.116 The MOS differential amplifier shown in Fig. P9.116 utilizes three current mirrors for signal transmission: Q4−Q6 has a transmission factor of 2 [i.e., (W/L)6/(W/L)4 = 2], Q3−Q5 has a transmission factor of 1, and Q7−Q8 has a transmission factor of 2. All transistors are sized to operate at the same overdrive voltage, |VOV|. All transistors have the same Early voltage |VA|.
where RSS is the output resistance of the bias current source I. (Hint: Since the input differential circuit is balanced, each of Q1 and Q2 will conduct a common-mode signal current of approximately (vicm/2RSS). These currents are fed into the current mirror loads. Use the current-mirror equivalent circuit derived in Section 8.2.5. Specificially, for each current mirror, the current transfer ratio is given by
where gm and ro are the parameters of the input transistor of the mirror.)