A MOS differential pair operated at a bias current of 0.8 mA employs transistors with W/L = 100 and μnCox = 0.2 mA/V2, using RD = 5 kΩ, and RSS = 25 kΩ. (a) Find the differential gain, the common-mode gain, and the common-mode rejection ratio (in dB) if the output is taken single-endedly and the circuit is perfectly matched. (b) Repeat (a) when the output is taken differentially. (c) Repeat (a) when the output is taken differentially but the drain resistances have a 1% mismatch. Ans. (a) 10 V/V, 0.1 V/V, 40 dB; (b) 20 V/V, 0 V/V, ∞ dB; (c) 20 V/V, 0.001 V/V, 86 dB
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A MOS differential pair operated at a bias current of 0.8 mA employs transistors with W/L = 100 and μnCox = 0.2 mA/V2, using RD = 5 kΩ, and RSS = 25 kΩ. (a) Find the differential gain, the common-mode gain, and the common-mode rejection ratio (in dB) if the output is taken single-endedly and the circuit is perfectly matched. (b) Repeat (a) when the output is taken differentially. (c) Repeat (a) when the output is taken differentially but the drain resistances have a 1% mismatch. Ans. (a) 10 V/V, 0.1 V/V, 40 dB; (b) 20 V/V, 0 V/V, ∞ dB; (c) 20 V/V, 0.001 V/V, 86 dB
