(a) For the MOS current buffer equivalent of we can write Zo 5 Zo1//Zo2, where Zo2 is the impedance presented by Cgd 1 Cdb, and Zo1 5 Ro1 1 1y(sCo1) is the impedance presented by the rest of the...

(a) For the MOS current buffer equivalent of we can write Zo 5 Zo1//Zo2, where Zo2 is the impedance presented by Cgd 1 Cdb, and Zo1 5 Ro1 1 1y(sCo1) is the impedance presented by the rest of the circuit. Obtain expressions for Ro1 and Co1, and then prove Eq. (6.78). (b) Assuming gm 1 gmb 5 0.5 mA/V, ro 5 20 kV, Cgs 1 Csb 5 450 fF, and Cgd 1 Cdb 5 100 fF, sketch and label the magnitude plots of Zo1(jf), Zo2(jf), and Zo(jf) using the impedance-plotting techniques of Appendix 6A. (c) How does the plot of Zo(jf) change if the signal source, instead of being ideal, has a parallel resistance Rsig 5 30 kV?