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110 年 - 110 國立臺灣大學_碩士班招生考試_電信工程研究所甲組:電子學(C)#101290 

選擇:0題,非選:14題 我要補題 回報試卷錯誤
【非選題】
1.

1. The closed-loop circuit in Fig. 1 can be used as an oscillator.
6142b12921200.jpg


【題組】(a) Please derive the condition to satisfy the Barkhausen criterion. What is the oscillation frequency? [10%]



【非選題】
2.【題組】

(b) Given that R = 10 kΩ, how do you choose RFand C to have an oscillation frequency of 100 kHz? [10%]



【非選題】
3.
2. For a MOSFET, the parameters are given as In Cox(W/L ) = 8 MA/V2, Vt= 1V and VA = 20 V. If the MOSFET is operated in saturation with a dc current of I, the transconductance is identical to that of a BJT operating in active mode with a dc current of 0.1I.

【題組】(a) Find the value ofI. [5%]


【非選題】
4.【題組】(b) What is the small-signal output resistance (ro) of the MOSFET? [5%]

【非選題】
5.【題組】(c) Find the intrinsic gain of the MOSFET. [5%]

【非選題】
6.【題組】(d) If the BUt has the same value of Vo, find the intrinsic gain of the BJT operating at a dc current of 0.1I. [5%]

【非選題】
7.

3. At higher frequencies, the MOSFET is characterized by its small-signal model by including6142b2325704c.jpg6142b2589bcc5.jpg


【題組】(a) The high-frequency current gain of the MOSFET is typically evaluated by the circuit in Fig. 3. Derive the transfer function of the current gain T(s) = Io/Is. [5%]


【非選題】
8.【題組】

(b) Based on T(s), find the unity-gain frequency ωt by assuming6142b2a71b781.jpg is relatively small. [5%]



【非選題】
9.【題組】

(c) For fixed DC voltage 6142b2e9db89a.jpg, how does ωt  change as channel width doubles? Why? [5%]



【非選題】
10.【題組】(d) For fixed DC voltage  6142b2e9db89a.jpg, how does  ωt  change as channel length doubles? Why? [5%]

【非選題】
11.

4. For the circuit in Fig. 4, assume the op-amp is ideal and the resistors are given as R = 5 kΩ, R1 = 10 kΩ, and R2 - 20 kΩ.
6142b3838d9a7.jpg


【題組】

(a) Given6142b349ea68e.jpg A for the diodes, find the output voltage when b,VI = 1 V. [5%]



【非選題】
12.【題組】(b) If the diodes are ideal, plot the voltage transfer curve (plot of Vo versus VI). Find the output voltage when  V= 1 V. [10%]

【非選題】
13.

5. Assume C1 and C2 are ideal coupling capacitors for the circuits in Fig. 5.
6142b3f75997e.jpg6142b412606b9.jpg


【題組】

(a) For the circuit in Fig. 5(a), find the input resistance6142b446a54d4.jpg, output resistance (RO) and open-circuit voltage gain6142b47322c33.jpgof the amplifier. [15%]



【非選題】
14.【題組】(b) For the circuit in Fig. 5(b), find the bias current I needed to obtain a voltage gain (vo/vs) of 15. [10%]

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110 年 - 110 國立臺灣大學_碩士班招生考試_電信工程研究所甲組:電子學(C)#101290-阿摩線上測驗

110 年 - 110 國立臺灣大學_碩士班招生考試_電信工程研究所甲組:電子學(C)#101290