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

科目：研究所、轉學考(插大)◆電子學 | 年份：110年 | 選擇題數：0 | 申論題數：14

試卷資訊

所屬科目：研究所、轉學考(插大)◆電子學

選擇題 (0)

申論題 (14)

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

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

(a) Find the value ofI. [5%]

(b) What is the small-signal output resistance (r_o) of the MOSFET? [5%]

(c) Find the intrinsic gain of the MOSFET. [5%]

(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%]

(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) = I_o/I_s. [5%]

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

(c) For fixed DC voltage , how does ω_t change as channel width doubles? Why? [5%]

(d) For fixed DC voltage

, how does ω_t change as channel length doubles? Why? [5%]

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

(b) If the diodes are ideal, plot the voltage transfer curve (plot of Vo versus V_I). Find the output voltage when V_I= 1 V. [10%]

(a) For the circuit in Fig. 5(a), find the input resistance, output resistance (R_O) and open-circuit voltage gainof the amplifier. [15%]

(b) For the circuit in Fig. 5(b), find the bias current I needed to obtain a voltage gain (v_o/v_s) of 15. [10%]