Question

Provided a cascade multistage amplifier network, their pole frequencies obtained are f1=10Mhz, f2=12Mhz, f3=20Mhz, f4=16Mhz. What is the approximate higher cutoff frequency of the cascaded network?

(a) 3.4 Mhz

(b) 8 Mhz

(c) 5 Mhz

(d) 6 Mhz

The question was asked during an interview.

I'd like to ask this question from Cascaded Amplifier in division General and Feedback Amplifiers of Analog Circuits

Answer 1

Right answer is (a) 3.4 Mhz

Easy explanation: The net frequency

1/fH = 1/f1 + 1/f2 + 1/f3 + 1/f4 and so on for multiple stages.

1/fH = 0.295833

fH ≈ 3.4 Mhz.