*9.22 The circuit of Fig. P9.22 shows an effective way of implementing the resistance Rs needed for the circuit in Fig. P9.20. Here Rs is realized as the series equivalent of two MOSFETs Q3 and Q4 that are operated in the triode region, thus, Rs = rDS3 + rDS4. Assume that Q1 and Q2 are matched and operate in saturation at an overdrive voltage VOV that corresponds to a drain bias current of I/2. Also, assume that Q3 and Q4 are matchedand Q4? At what overdrive voltages are Q3 and Q4 operating? Find an expression for rDS for each of Q3 and Q4 and hence for R s in terms of (W/L)1,2, (W/L)3,4, and gm1,2. (b) Now with vG1 =vid/2 and vG2 =−vid/2, where vid is a small signal, find an expression of the voltage gain A d ≡vod/vid in terms of gm1,2, RD, (W/L)1,2, and (W/L)3,4.

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images - *9.22 The circuit of Fig. P9.22 shows an effective way of implementing the resistance Rs needed for the circuit in Fig. P9.20. Here Rs is realized as the series equivalent of two MOSFETs Q3 and Q4 that are operated in the triode region, thus, Rs = rDS3 + rDS4. Assume that Q1 and Q2 are matched and operate in saturation at an overdrive voltage VOV that corresponds to a drain bias current of I/2. Also, assume that Q3 and Q4 are matchedand Q4? At what overdrive voltages are Q3 and Q4 operating? Find an expression for rDS for each of Q3 and Q4 and hence for R s in terms of (W/L)1,2, (W/L)3,4, and gm1,2. (b) Now with vG1 =vid/2 and vG2 =−vid/2, where vid is a small signal, find an expression of the voltage gain A d ≡vod/vid in terms of gm1,2, RD, (W/L)1,2, and (W/L)3,4.

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