Question

At what frequency, the phase shift between input &output voltage will be zero?

(a) -40Hz

(b) 0Hz

(c) -22Hz

(d) 20Hz

I have been asked this question during an interview for a job.

The doubt is from Open-Loop Voltage Gain as a Function of Frequency topic in section Practical Limitations of Op Amp Circuits of Linear Integrated Circuits

Answer 1

The accurate choice is (b) 0Hz

For a clear picture: At 0Hz the phase shift between input and output voltage is zero.

At f=0Hz, φ(f) = – tan^-1 (f/fo) = -tan^-1(0/5) = 0^o