Review question 2021.06 1、 （10 points） For the circuits shown in Figure 1(a)，vs＝10sinwt（V）. For the diode Vγ= 0.7V, Sketch the waveform of vL。 vS 10V π O 2π 4π 3π ωt vL ＋ D4 D1 vS ＋ D3 D2 － RL O vL π 2π 4π ωt 3π － （a） （b） Figure 1 2.． （22 points） For the circuit in Figure 2, let β=100, VBE(on)=0.7V ,VA=100V, all the capacitors are assumed to act as short circuits at the signal frequency. ① Calculate the Q-point (IB, IC, VCE); ② Sketch the small-signal equivalent circuit; ③ Determine the input resistance Ri=vI/is; ④ Determine the small-signal voltage gain Av=vO/vI and Avs=vO/vs; ⑤ Determine the output resistance Ro. VCC Rb1 27k C1 Rs 10k ＋ vs － is 20uF vI Rb2 15k C2 + 20uF 2.2k + + 9V Rc T RL 2k Re 1.2k Figure 2 共8页 第 1 页 + io + Ce 100uF vO 3． （22 points） For the circuit in Figure 3, for transistor T2, β is known, VA=∞, for transistor T1, gm is known, and λ=∞, all the capacitors are assumed to act as short circuits at the signal frequency. ① Sketch the small-signal equivalent circuit; ② Determine the expression of the input resistance Ri=vI/ii; ③ Determine the expression of the small-signal voltage gain Av=vO/vI ; ④ Determine the output resistance Ro. Figure 3 4. Score 共8页 第 2 页 5.（2 problems, a total of 16 points） 1) For the circuit in Figure 3-1, assume all the op-amps are ideal, Determine the output voltage VO. Figure 3-1 2) For the circuit in Figure 3-2, assume all the op-amps are ideal, VBE = 0.7V when BJT is in turn-on. （1）Determine the voltages at node c, b and e ; （2）When two BJT are connected in the circuit one after another, the voltmeter readings is 200mV . Determine the β of the BJT. R3 c R1 +10V 5k + +5V A1 20k b T A2 e vO + R2 5k R V Figure 3-2 Score 4.（10 points） The Zener diode voltage in Figure 4 is VZ = 6V and minimum current is Izmin=5mA, VI =12V, R=100Ω. （1）Determine the maximum value of IL; （2）What is maximum power dissipation of DZ at least ? 共8页 第 3 页 Figure 4 Score 5.（18 points） For the circuit in Figure 5, let β=40, VBE = 0.7V, all the capacitors are assumed to act as short circuits within the passband. (1) Determine Q-pint (IBQ, ICQ, VCEQ); (2) Sketch the small-signal equivalent circuit of the amplifier; (3) Within the passband, determine the voltage gain Av=vo/vi 、input resistance Ri and source voltage gain Avs = vo / vs . 图3 + vi Figure 5 共8页 第 4 页 Score 6.（3 problems, a total of 21 points） 1）For the circuit in Figure 6-1, assume MOSFET is biased in the saturation region and gm= 2 mS, all the capacitors are assumed to act as short circuits within the passband.. （1）The small-signal voltage gain |Av| =___________； +10V A. 10 B. 20 C. 100 Rd （2）The output resistance Ro =___________ k。 10k C1 + A. 5 B. 10 C. 20 + R L vo T 10k + vi + Cs Rs VGG Figure 6-1 3）For the circuit in Figure 6-3, | VCES | is the saturation voltage drop of T1 and T2, the maximum possible power that can be delivered to RL is Pom =____B_______。 A. V CC2 RL V CC2 C. 8R L B. (V CC | V CES | )2 2R L V CC ( D. 2 +VCC vi | V CES | ) T1 C 2 T2 2R L －VCC Figure 6-3 共8页 RL 第 5 页 vo Score 7.（1 problems, a total of 10 points） For the circuit in Figure 7-1, let the differential-mode voltage gain is 100 in one-sided output and the CMRR is 40dB. If vs =20mV, then: （1）the differential-mode input voltage vid =_C_, the common-mode input voltage vic =__B; A. 5mV B. 10mV C. 20mV D. 40mV （2）the output voltage vo =_D__ that caused by vs. A. 2V B. 2.1V C. 2.01V D. 1.99V +VCC Rc Rc vO T1 T2 + vs IO ro -VEE Figure 7-1 共8页 第 6 页 （ （