Question

Find the range of frequency between which the circuit act as integrator?

(a) [1/(2πRFCF)]– (2πR1CF)

(b) (2πRFCF) – [1/(2πR1CF)].

(c) [1/(2πRFCF)]- [1/(2πR1CF)].

(d) None of the mentioned

I have been asked this question during an interview.

Enquiry is from Integrator in division Operational Amplifier Applications of Linear Integrated Circuits

Answer 1

The correct choice is (c) [1/(2πRFCF)]- [1/(2πR1CF)].

Break it down: For a practical integrator, the gain limiting frequency is fa= 1/(2πRF CF). After fa, the gain decreases at a rate 20db/decade and reaches 0db. The frequency at which gain is 0db is fb= 1/(2π RF×CF). So, the circuit act as integrator between fa and fb.