This set of Linear Integrated Circuit Multiple Choice Questions & Answers (MCQs) focuses on “DC and AC Amplifiers”.
1. An inverting amplifier that amplifies dc input level is called
a) DC and AC amplifier
b) AC amplifier
c) DC amplifier
d) None of the mentioned
Explanation: In a DC amplifier, the output signal changes it response to changes in its dc input level. A DC amplifier can be inverting, non-inverting or differential.
2. Find the DC differential amplifier with offset null circuitry?
Explanation: The mentioned circuit is the DC differential amplifier, since DC voltage is applied to the differential inputs of the amplifier.
3. Why DC amplifier uses offset null circuitry?
a) To reduce the distortion in output
b) To improve the accuracy of amplifier
c) To get large output gain
d) All of the mentioned
Explanation: A DC amplifier uses offset null circuitry to reduce the output offset voltage to zero, that is , to improve the accuracy of DC amplifier.
4. Why are coupling capacitor used in audio receiver system?
a) All of the mentioned
b) Thermal drift
c) Component tolerance
d) Variation in signal
Explanation: An audio receiver system consists of a number of stages because of thermal drift, components tolerance and variation, which introduces a dc level. To prevent the amplification of such dc level, the coupling capacitors are used.
5. Find the AC inverting amplifier from the circuits given below?
Explanation: AC amplifier consists of external offset voltage compensating network. Therefore, the external offset voltage is connected to the non-inverting input terminal of the amplifier.
6. Determine the bandwidth of the AC inverting amplifier for high cut-off frequency of 15 Hz?
Explanation: Input resistance RIF=R1=100Ω (for ideal inverting amplifier).
=> The source resistance RIN=RO=5kΩ.
Therefore, Low frequency cut-off, fL=1/2πCi(RIF+RO) = 1/ [2π×4.7µF×(5kΩ+100Ω)] = 6.64Hz. and the bandwidth is calculated as, BW= fH-fL = 15Hz-6.64Hz = 8.356Hz.
Sanfoundry Global Education & Learning Series – Linear Integrated Circuit.