(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.

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

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

 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.

(a) (10%) Determine VG.

(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.

4. (30%) Figure 4 shows a CC-CE amplifier with = RL = 5 kΩ, I1 = I2 = 1mA, and identical transistors with β = 100, fT = 500 MHz, Cμ = 5pF, and Cc = 2uF. The thermal voltage VT= 25mV. For simplicity, neglect ro and rx effect. Please find (a) the input resistance(b) the midband gain AM, (c) the Cπof the BJTs, and (d) 3-dB frequency of the upper end of the midband, fH (using open-circuit time- constants method). (5%, 5%, 5%, 15%)

3. (30%) Figure 3 is the two-stage CMOS op amp configuration. All NMOSFETs have the same W/L = 10um/0.5um, = 0.5V, = 200 uA/V2. All PMOSFETs have the same WIL = 40um/0.5pμm, = -0.5V, = 50 μA/V2. IVAI (for all devices) = 100μ.A. Neglect the effect of VA on bias current. Please find (a) the transconductance gm and ro of Q2, (b) the voltage gain of the furst stage A1 and the second stage A2, (c) the input common-mode range, and (d) the output voltage range.(10%, 10%, 5%, 5%)

2.(25%) Consider the voltage amplifier of Figure 2 with a BJT device having β =100 when it is biased in the active region, the AC signal voltage Vsig, signal resistance = 10kΩ and coupling capacitors and which can block DC component and pass AC component. The voltage supplies = 10V and the thermal voltage VT= 25mV. The constant voltage drop 0.7V approximation can be used for the turn- on of a p-n junction, and the constant voltage drop ~ 0.2V approximation can be used when the BJT is biased in the saturation region. In addition, other resistances are also included, such like R1 = 2MΩ, R2 = 2MΩ, RE = 5kΩ, Rc = 5kΩ, RL= 5kΩ. Please come out following parameters: (a) transconductance gm, (b) input resistance, (c) overall AC voltage gain (d) Please describe the advantages of the existing of emitter resistance Re compared with no RE. (5%, 5%, 5%, 10%)

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