Question

ercise 2 Part One: Verify the operation modes of various transistor configurations fask 2.1.1: atermine the input resistance, output resistance, small-signal voltage gain and low-frequency cut-off of the circuits in Figure 2.2, given that gm 3mS for the circuit on the left and 24mS for the circuit on the right. You may assume that CS has been chosen so that its impedance is 'small' at the frequencies of interest. Use simulation to verify your solution. V DD 15 V Voo-12 V Rp= 4 kn Ro 47 k2 R 4 MQ C 1 pF 27 nF HH Rç= R 2 MO Rs 1 k2 2 MQ Cs Vss (0 V) Figure 2.2 Example MOSFET amplifier circuits (Storey, 2009) Vss (0 V) Task 2.1.2: Using a circuit of the form shown in Figure 2.3, design an amplifier with a small-signal voltage gain of -3, quiescent output voltage of 7 V, supply voltage of 12 V and collector load resistance of 2.2 ko. Calculate the small-signal input resistance and then determine an appropriate value for the input capacitor to allow satisfactory operation at frequencies down to 50 Hz. Use simulation to confirm the operation of your solution. -Vc12 V R R= 3.9 k 9.8 kQ Rg R2= 2.2 k2 1 kQ Figure 2.3 Example BJT amplifier circuit (Storey, 2009)

Answer 1

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AVOD Ro * Vo C R2 Smoi) signal Ac Eauivalent circujt RD Rull R2 isgmVgs Kn Rin= input resistence Ri) R2 4112 412- Ro output resistance- RD 4 7 Kn Av Voltegt gain: -9m RD 112. wM 444 0PF Froquen tg due to capecitor C 750 Rdls 1 C.Rin K