Question

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

I got this question during an online interview.

My doubt stems from High Frequency Response in division Transistor Frequency Response of Analog Circuits

Answer 1

Correct choice is (a) 7.8 x 10^6 rad/s

For explanation I would say: The frequency in radians is calculated by

 ωβ = 1/C.rbe

ωβ = 7.8 x 10^6.