Question 3.SP.14: For the amplifier of Fig. 3-17, CC = 100 μF, RF = 180 kΩ, RL......
For the amplifier of Fig. 3-17, C_C = 100 μF, R_F = 180 kΩ, R_L = 2 kΩ, R_S = 100 kΩ, V_{CC} = 12 \text{V}, and v_S = 4 \sin(20 × 10^3πt) \text{V}. The transistor is described by the default npn model of Example 3.2. Use SPICE methods to (a) determine the quiescent values (I_{BQ}, I_{CQ}, V_{BEQ}, V_{CEQ}) and (b) plot the input and output currents and voltages (v_S, i_S, v_L, i_L).
(a) The netlist code that follows models the circuit:
| Prb3_14.CIR – CE amplifier vS 1 0 SIN(0V 4V 10kHz) RS 1 2 100kohm CC1 2 3 100uF Q 4 3 0 QNPN RF 3 4 180kohm RC 4 5 2kohm VCC 5 0 12V CC2 4 6 100uF RL 6 0 2kohm .MODEL QNPN NPN() ; Default transistor .DC VCC 12V 12V 1V .PRINT DC IB(Q) IC(Q) V(3) V(4) .TRAN 1us 0.1ms ; Signal values .PROBE .END |
Execute 〈Prb3_14.CIR〉 and poll the output file to find I_{BQ} = IB(Q) = 29.3 μ\text{A}, I_{CQ} = IC(Q) = 2.93 \text{mA}, V_{BEQ} = V(3) = 0.80 \text{V}, and V_{CEQ} = V(4) = 6.08 \text{V}. Since V_{CEQ} \simeq V_{CC}/2, the transistor is biased for maximum symmetrical swing.
(b) The Probe feature of PSpice is used to plot i_S, i_L, v_S, and v_L as displayed by Fig. 3-18. Notice the 180° phase shift between input and output quantities.
