This set of Linear Integrated Circuit Multiple Choice Questions & Answers (MCQs) focuses on “Integrator-1″.
1. The circuit in which the output voltage waveform is the integral of the input voltage waveform is called
c) Phase shift oscillator
d) Square wave generator
Explanation: Integrator circuit produces the output voltage waveform as the integral of the input voltage waveform.
2. Find the output voltage of the integrator
a) Vo = (1/R×CF)×t∫0 Vindt+C
b) Vo = (R/CF)×t∫0 Vindt+C
c) Vo = (CF/R)×t∫0 Vindt+C
d) Vo = (R×CF)×t∫0 Vindt+C
Explanation: The output voltage is directly proportional to the negative integral of the input voltage and inversely proportional to the time constant RCF.
Vo = (1/R×CF)×t∫0 Vindt+C
Where C-> Integration constant and CF-> Feedback capacitor.
3. Why an integrator cannot be made using low pass RC circuit?
a) It require large value of R and small value of C
b) It require large value of C and small value of R
c) It require large value of R and C
d) It require small value of R and C
Explanation: A simple low pass RC circuit can work as an integrator when time constant is very large, which require large value of R and C. Due to practical limitations , the R and C cannot be made infinitely large.
4. How a perfect integration is achieved in op-amp?
a) Infinite gain
b) Low input impedance
c) Low output impedance
d) High CMRR
Explanation: In an op-amp integrator the effective input capacitance becomes CF×(1-Av). Where Av is the gain of op-amp. The gain is infinite for ideal op-amp. So, effective time constant of the op-amp integrator becomes very large which results in perfect integration.
5. The op-amp operating in open loop result in output of the amplifier to saturate at a voltage
a) Close to op-amp positive power supply
b) Close to op-amp negative power supply
c) Close to op-amp positive or negative power supply
d) None of the mentioned
Explanation: In practice, the output of op-amp never becomes infinite rather the output of the op-amp saturate at a voltage close to op-amp positive or negative power supply depending on the polarity of the input dc signal.
6. The frequency at which gain is 0db for integrator is
Explanation: The frequency at which the gain of the integrator becomes zero is f=1/(2πR1CF).
7. Why practical integrator is called as lossy integrator?
a) None of the mentioned
b) Provide stabilization
c) Changes input
d) Dissipation power
Explanation: To avoid saturation problems, the feedback capacitor is shunted by a feedback resistance(RF). The parallel combination of RF and CF behave like a practical capacitor which dissipates power. For this reason, practical integrator is called as a lossy integrator.
8. Determine the lower frequency limit of integration for the circuit given below.
Explanation: The lower frequency limit of integration, f= 1/(2πRFCF) = 1/(2π×1kΩ×33nF) = 4.82kHz.
Sanfoundry Global Education & Learning Series – Linear Integrated Circuit.