# Category: sedra and smith #### |. (25 points) Consider the following circuit. Ryy=5 k82, Ri=33 k8, R2=22kQ, Re=3.9kQ, Re=4.7kQ, Ri=5.6kQ, Vec=S5V. Also her=120, Va=60V, and r.=509. (a) (15 points) Find the midband voltage gain, input and output resistances. (b) (5 points) If fo1=/p3=10 Hz and fp2=100 Hz, estimate the lower 3-dB frequency /.. (c) (5 points) If required fi. is to be less than 50 Hz, find the smallest Cr.

... #### 2. (25 points) The circuit below shows an amplifier fed with a signal current isig having a source resistance Rag=10k. The BJT is specified to have hre=100, Cu=0.5pF, and Va=50V. (1) C15 points) Using the open-circuit time constant method, find the time constant associated with Cy. (2) (10 points) If the time constant associated with C; is 50 ns, estimate the fi.

... #### 4. (25 points) Consider the feedback amplifier circuit below. Assume gai=ga2=5MA/V, Tot=To2=50kQ, Ro=Rs=10kQ, and Re=90k2. (1)(5 points) What is the feedback configuration and what is the intended amplification function? (2) (5 points) Draw the feed-back circuit and find the feedback factor B. (3) (5 points) Draw the A-circuit. (4) (10 points) If it is found from the A-circuit that A=-555, Ri=100kQ, and Ro=30kQ, find Ay, Rus, Roy, Rin, and Row as marked on the circuit.

... #### The discrete-circuit CS amplifier shown is biased to operate at gm=3mA/V, and has the following component values: Rsig=1001M, RG1=47A/K2, RG2=10MS2, RS=21d2, RD=4.71M, and RL=10ka ro = 1001a Cgs = 1pF, and Cgd = 0.2pE Find the mid-band gain AM and the high frequency cutoff fH. v DD (a) R Cc,

... #### 2) For the amplifier shown VCC=5V; Rsig=51d2, RB1=33kf2, RB2=221M, RE=3.9kf2, RC=4.71c12, RL=5.6kf2, the collector bias current is 0.3mA and fi is 120. a) Find the input resistance Rin and the mid-band gain AM b) If CC1 =CC2 =1,uF and CE =20,uF, find fL using the short-circuit time constant method. Vsig VCC (a) C.’ ■

... ...