# High Frequency Response MCQ’s

This set of Analog Electronic Circuits Multiple Choice Questions & Answers (MCQs) focuses on “High Frequency Response”.

1. Consider a CE circuit, where trans-conductance is 50mΩ^{-1}, diffusion capacitance is 100 pF, transition capacitance is 3 pF. I_{B} = 20μA. Given base emitter dynamic resistance, r_{be} = 1000 Ω, input V_{I} is 20*sin(10^{7}t). What is the short circuit current gain?

a) 30

b) 35

c) 40

d) 100

2. Given that transition capacitance is 5 pico F and diffusion capacitance is 80 pico F, and base emitter dynamic resistance is 1500 Ω, find the β cut-off frequency.

a) 7.8 x 10^{6} rad/s

b) 8.0 x 10^{6} rad/s

c) 49.2 x 10^{6} rad/s

d) 22.7 x 10^{6} rad/s

3. We cannot use h-parameter model in high frequency analysis because ____________

a) They all can be ignored for high frequencies

b) Junction capacitances are not included in it

c) Junction capacitances have to be included in it

d) AC analysis is difficult for high frequency using it

4. For given BJT, β=200. The applied input frequency is 20 Mhz and net internal capacitance is 100 pF. What is the CE short circuit current gain at β cut-off frequency?

a) 200

b) 100

c) 141.42

d) 440.2

5. Gain bandwidth frequency is GBP= 3000 Mhz. The cut-off frequency is f=10Mhz. What is the CE short circuit current gain at the β cutoff frequency?

a) 212

b) 220

c) 300

d) 200

6. Given a MOSFET where gate to source capacitance is 300 pF and gate to drain capacitance is 500 pF. Calculate the gain bandwidth product if the transconductance is 30 mΩ^{-1}.

a) 5.98 Mhz

b) 4.9 Mhz

c) 6.5Mhz

d) 5.22Mhz

7. Given that β=200, input frequency is f = 20Mhz and short circuit current gain is A = 100. What is the unity gain frequency?

a) 2308 Mhz

b) 2000 Mhz

c) 2508 Mhz

d) 3000 Mhz

8. Which of the statement is incorrect?

a) At unity gain frequency the CE short circuit current gain becomes 1

b) Unity gain frequency is the same as Gain Bandwidth Product of BJT

c) Gain of BJT decreases at higher frequencies due to junction capacitances

d) β- cut-off frequency is one where the CE short circuit current gain becomes β/2

9. In an RC coupled CE amplifier, when the input frequency increases, which of these are incorrect?

a) Reactance C_{SH} decreases

b) Voltage gain increases

c) Voltage gain decreases due to shunt capacitance

d) An RC coupled amplifier behaves like a low pass filter

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