(a) Replace the FET of Fig. P3.49 with its smallsignal model, and use the test-signal method to fi nd Rgs. (b) Calculate Rgs if RF 5 1 MV and RD 5 10 kV, and the FET has gm 5 1 mA/V and ro 5 100 kV....

(a) Replace the FET of Fig. P3.49 with its smallsignal model, and use the test-signal method to fi nd Rgs. (b) Calculate Rgs if RF 5 1 MV and RD 5 10 kV, and the FET has gm 5 1 mA/V and ro 5 100 kV. (c) Investigate the limiting case RF → 0 and RD → `, and justify in terms of known FET properties. (d) Repeat, but for the case RF @ RD, RD now being fi nite. (e) What happens in the limit RD → 0?