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Unformatted text preview: ECE3050 Assignment 11 1. The f gure shows the ac signal circuit of a cascade commonsource ampli f er. For each MOS FET, it is given that I D = 2mA , r = ∞ , and K = 0 . 25 × 10 − 3 A / V 2 . The circuit element values are R S = 1k Ω , R S 1 = R S 2 = 510 Ω , R D 1 = R D 2 = 15k Ω . (a) Show that g m 1 = g m 2 = 1 . 414mS and r s 1 = r s 2 = 707 . 1 Ω . (b) Use the T models or simpli f ed T models to show that the voltage gain is given by v o v s = − R D 1 r s 1 + R S 1 × − R D 2 r s 2 + R S 2 = 152 (43 . 6dB) (c) Use the π models to show that the voltage gain is given by v o v s = − R D 1 1 g m 1 + R S 1 × − R D 2 1 g m 2 + R S 2 = 152 (43 . 6dB) (d) Show that the input resistance is given by r in = ∞ (e) Show that the output resistance is given by r out = R D 2 = 15k Ω (f) What would be the new gain if a resistor R L = 1k Ω is connected from output to ground?...
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 Summer '08
 HOLLIS
 The Circuit, Voltage drop, Buffer amplifier, Output impedance

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