The circuit in Figure P9.65 is a representation of the common-mode and differential-input...

The circuit in Figure P9.65 is a representation of the common-mode and differential-input signals to a difference amplifier. The output voltage can be written as

υo =Ad υd +Acm υcm

where Ad is the differential-mode gain and Acm is the common-mode gain.

(a)    Setting υd = 0, show that the common-mode gain is given by

(b)   Determine Acm if R1 = 10.4 kΩ, R2 = 62.4 kΩ, R3 = 9.6kΩ, and R4 = 86.4kΩ. (c) Determine the maximum value of | Acm | if R1 = 20kΩ ± 1%, R2 = 80kΩ ± 1%, R3 = 20 kΩ ± 1%, and R4 = 80 kΩ ± 1%.