(b) Amplifier “A" has gain 30DB and noise figure 3.7 dB at the frequency of interest. Amplifier “B" has gain 20 dB and noise figure 8.4 dB at the same frequency. Input and output impedances are 50 Q throughout. I. When used in cascade, what is the combined noise figure? I. From the answer obtained for question 1(b) i, what can you say about the combined noise figure when compared to the large noise figure given in second stage?

4) Below is the small signal model of a multistage amplifier. Using this model, write the equationsthat you would need to determine the voltagegain. IMPORTANT: You only need to providethe equations that you would need to determinethe voltage gain. You DO NOT need to combine and simplify the equationsto determine a final expression for the voltagegain. Vin Vo Vb vo1 Rb R13 Vbe1 Vbe2 'e gm 1 Vbe1 gm 2 Vbe2 Rc2 Rc1 Re