Question

Open loop bandwidth of an op-amp extend its bandwidth from

(a) 0Hz to fo

(b) 20dB to fo

(c) 3dB to fo

(d) 0.704dB to fo

This question was addressed to me during a job interview.

I need to ask this question from Frequency Response of Internally Compensating and Non-Compensating Op-Amp topic in chapter Practical Limitations of Op Amp Circuits of Linear Integrated Circuits

Answer 1

The open loop bandwidth of an op-amp extends its bandwidth from 0Hz to fo (upper cutoff frequency). The correct answer is (a) 0Hz to fo. The open loop frequency response of an op-amp starts from DC (0Hz) and extends up to the cutoff frequency (fo), which is typically much lower than the closed-loop bandwidth due to internal frequency compensation. This bandwidth-gain tradeoff is fundamental to op-amp design.