| 4月28日 第3節 電子系乙組 | 誠實是我們珍視的美德， 我們喜愛「拒絕作弊，堅守正直」的你！ |
| 科目：電子學 | （共2頁 第1頁） |
| 1. | (a) Find the voltage transfer function T(s)of the STC (single-time-constant) low-pass circuit shown in Fig.1. (10%)  (b) Find the Bode plot for the phase of the T(s) obtained in part (a). (15%) |
| 2. | Design a second-order "high-pass" (Note: not "low-pass") Butterworth filter with the lower 3-dB cutoff frequency f0 = 5kHz. Draw its circuit diagram and find the resistances which are not indicated. (25%) Hint: (a) Consider the "low-pass" (Note: "not" "high-pass") filter using an ideal OP AMP with  Shown in Fig.2.  (b) The normalized (ω0 = 1 rad/sec ) second-order Butterworth polynomial is: s2+1.414s+1 (c) Note: If a student just designs a "low pass" Butterworth filter, the score that can get at most is 15. |
| 3. | The circuit shown in Fig.3 is an emitter-coupled pair in which Q3 and Q4 are used to bias Q1 and Q2. Transistors Q5, Q6, and Q7 form a current repeater, and Q6 and Q7 form the loads for Q1 and Q2. Assume VBE(on)npn = VEB(on)pnp = 0.7V, all pnp transistors
have βF = 50; the npn transistors have βF = 100. Assume VA → ∞. Find the following current and resistor values.
(a) IC3 = ? (b) IC6 = ? (c) IR2 = ? (d) R2 = ? (24%)  |
| 4. | Consider the CMOS common-source amplifier in Fig.4 for the case: VDD = 5V, Vtn =∣Vtp∣= 0.8V, μnCox = 2μpCox = 40 μA/V2,
Assume all transistors operate in the saturation region, and ∣VA∣=100V for both the n and p devices, and IREF = 100μA. Where (W/L)M1 = (W/L)M2, (W/L)M4 = 2(W/L)M1 (a) Find (W/L)M1 = ?, (W/L)M3= ? (10%) (b) Find the small-signal volatege gain. (16%) (Assume L = 2μm for all devices, and Vo(Q-point) = 2.5V)  |
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