This problem investigates the frequency response of the CE amplifi er to a source with a high resistance Rsig. (a) Show that if Rsig @ rb 1 r, the low-frequency gain can be estimated as a0 >...

This problem investigates the frequency response of the CE amplifi er to a source with a high resistance Rsig. (a) Show that if Rsig @ rb 1 r, the low-frequency gain can be estimated as a0 > 20[(RC//ro)y Rsig]. (b) Show that if gm(RC//ro)C @ C, the 23-dB frequency can be estimated as f23 dB > 1y[20(RC//ro)C], and the gain-bandwidth product as GBP > 1y(2RsigC). (c) Investigate the specifi c case of a BJT with 0 5 125, VA 5 75 V, rb 5 200 V, and C 5 1.0 pF. Assume the BJT is biased at IC 5 1 mA, and the external resistances are Rsig 5 30 kV and RC 5 10 kV. Hence, sketch and label the Bode plot of gain, and comment on your results.