106年 - 106 國立中山大學_碩士班招生考試_電波領域：電子學#110216

 (a)(10%) Estimate the quality factor of the equivalent smnall-signal LCR circuit seen at the collector

of Q.

 (b) (10%) If the sustained oscillation occurs, what will be the oscillation frequency (in Hz)?

 (c)(10%) Calculate the small-signal transconductance g_m of the transistor Q, and determine if the

feedback gain is large enough to cause oscillation. Justify your answer.

 2. (20%) Suppose we want to convert v(t)=cos(10t) to v(t) = Axsin(10t) by a phase shift circuit in Fig. 2. Determine the value of R, and what will be the output amplitude A in this case?

3. (20%) A series RC circuit is utilized to equalize the impedance of an inductive load in Fig. 3. Determine the value of C in Fig. 3 so that the overall impedance Z becomes a pure resistance of 50 ohm in the entire frequency band.

(b) (10%) Determine the minimum allowed that still assures that M works properly as a constant current source.

(c) (10%) Suppose the 15V supply voltage has 1% variations on it (i.e.,△ =± 0.15V). Estimate the percentage change in current Io. Notefor M in saturation.