Question

1. The common source amplfier shown below uses a dc-coupled input and the load capacitance has been removed. Assume that the high-frequency cutoff (-3dB) frequency f. is determined chiefly by R and the total input capacitance, which consists of Cg in parallel with the Miller effect capacitance reflected nto the input. Calculate and show the M coupling and bypass capacitors shown in the circuit can be treated as short-cicuits t capacitance, then estimate fs For this analysis, the R 10k Vov (overdrive voltage) 0.25V 150F C 25fF 0.DS 5K Ri Ce Now estimate the upper -3dB frequency fhof the common-source amplifier by means of the method of open-circuit time constants 2. The common-source amplifier of Problem 1 has been turned into a cascode amplifier by the addition of a common-gate output stage. The voltage V is a dc bias voltage for the gate of the common gate stage. For ac analysis, V is treated as any other dc voltage source (i e., a short circuit) 3. The total load resistance for the common-source stage is now the input resistance of the common-gate stage Rin in parallel with output resistance ro of the common source stage. Calculate Rn and use this value in computing the input Miller capacitance for the cascode amplifier. Then re-estimate fu R.