Question

The unity gain bandwidth for an op-amp having open loop gain 2×10^6 is 10 Mhz. Calculate the AC gain of op-amp at an input of 2000 Hz.

(a) 2000

(b) 5000

(c) 10000

(d) 12.5

The question was asked in an interview for job.

My query is from Operational Amplifiers in chapter Op-amps and its Applications of Analog Circuits

Answer 1

Right option is (b) 5000

For explanation: UGB = AOLfOL

fOL = 10M/2×10^6 = 5Hz

The AC gain |A| = \(\frac{AOL}{\sqrt{1+(f/5)^2}}\)

|A| = 2×10^6/400 = 5000.