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A common-source amplifier is shown below. The MOSFET parameters are k'n = 2mA/V2, VT = 0.8 V. The amplifier is biased with a source VDD = 5 V, and resistors RD = 4 kohm, RS = 1 kohm, RG1 = 225 kohm, RG2 = 175 kohm, Vov = 0.75 V (a) Calculate the drain current ID. Recall the formula for a MOSFET in saturation: ID = 1/2k'n(VGS - VT)2 (b) Obtain the MOSFET voltage vDS. (c) Using small-signal analysis, obtain the voltage gain vo/vi for RL = 12 kohm. Assume ro = 100 kohm, gm = 1 mA/V.

A common-source amplifier is shown below. The MOSFET parameters are k'n = 2mA/V2, VT = 0.8 V. The amplifier is biased with a source VDD = 5 V, and resistors RD = 4 kohm, RS = 1 kohm, RG1 = 225 kohm, RG2 = 175 kohm, Vov = 0.75 V (a) Calculate the drain current ID. Recall the formula for a MOSFET in saturation: ID = 1/2k'n(VGS - VT)2 (b) Obtain the MOSFET voltage vDS. (c) Using small-signal analysis, obtain the voltage gain vo/vi for RL = 12 kohm. Assume ro = 100 kohm, gm = 1 mA/V.

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A common-source amplifier is shown below. The MOSFET parameters are k'n = 2mA/V2, VT = 0.8 V. The amplifier is biased with a source VDD = 5 V, and resistors RD = 4 kohm, RS = 1 kohm, RG1 = 225 kohm, RG2 = 175 kohm, Vov = 0.75 V (a) Calculate the drain current ID. Recall the formula for a MOSFET in saturation: ID = 1/2k'n(VGS - VT)2 (b) Obtain the MOSFET voltage vDS. (c) Using small-signal analysis, obtain the voltage gain vo/vi for RL = 12 kohm. Assume ro = 100 kohm, gm = 1 mA/V.

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For this problem, neglect capacitances and ro in transistors and use long-channel equations. M1 is operated with Vov = 0.6 V. The amplifier is intended to be used with a source resistance RS = 50 Ω. (a) Calculate (W/L)1 for an input impedance equal to 50 Ω. What is the required ID1? (b) If (W/L)2 = (W/L)3 what is the required value if I bias ? (c) Calculate R for a voltage gain vo/vi = 10 (d) Symbolically, calculate the NF considering the contribution of M1, M2 and R. (e) To reduce noise figure, is it better to use a high or a low overdrive in M2 and M3? Explain why. (f) If |Vov2| = 1 V, calculate (W/L)2, the DC component at vo and F in dB. CMOS process data: VDD = 1.8 V. For NMOS, Vthn = 0.4 V, μn = 400 cm2/Vs, Cox = 9 fF/μm2 and γn = 1. The parameters for PMOS transistors are k′ = μpCox = 90 μA/V2, Vthp = −0.4 V and γp = 0.8.
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