MCQs on Analog Electronics
01․ The feedback factor of a Wien bridge oscillator using Op-Amp is
At the resonant frequency, the feedback factor (R2/R1) of a Wien bridge oscillator using Op-Amp, is 1/2. Hence, the amplifier gain must be greater than 2 to maintain sustained oscillations.
02․ For audio frequency applications, the popular oscillator used is
Characteristics like ease of tuning, very low distortion and good frequency stability of Wien bridge oscillator makes it becomes popular for audio frequency applications. Phase shift oscillator and Wien bridge oscillator both can be used as audio frequency range. But Wien bridge oscillator can be used for very wide frequency range.
03․ Colpitts oscillator is also called as
Colpitts oscillator is one of the type of LC oscillator which consisting of resonant tank circuit. The tank circuit consists of two series capacitor parallel with a inductor. Therefore, we can call any of the names mentioned above.
04․ A quartz crystal oscillator consists of
Crystal Oscillator has two closely spaced resonant frequency. In crystal oscillator, series resonant frequency occurs when reactance of the capacitor is equal to the reactance of the inductor (low impedance). Parallel resonant frequency occurs when reactance of the capacitor C2 is equal to the reactance of RLC1 branch (High impedance).
05․ Which oscillators are easy to fabricate in a monolithic IC?
Relaxation oscillators do not use inductor and its output depends on nonlinear characteristics of the circuit. Therefore, a relaxation can be easily fabricated in a monolithic IC's.
06․ Which of the following is not a sinusoidal oscillator?
Relaxation oscillator is basically a non-sinusoidal oscillator which is used to generate square, triangular or pulse waveforms. The rest of the oscillators are sinusoidal oscillators producing sinusoidal output.
07․ Voltage controlled oscillators are used commonly in
VCOs are commonly used in electronic jamming equipment, function generator, for production of different types of noise, phase locked loop, frequency synthesizers or modulators used in communication circuits etc.
08․ One of the following is the primary function of an oscillator
The oscillating nature of a circuit make it as oscillator. But to produce sustained oscillations in a controllable and desired manner and has to satisfy Bark-hausen criterion.
09․ Relaxation Voltage controlled oscillators are used to generate
Relaxation VCOs can be employed to generate both triangular and saw-tooth waveforms.
10․ Feedback circuit in an oscillator can be accomplished by
For different type of applications, oscillators can be built with different feedback circuit to produce proper phase and amplitude. These types of oscillators include RC and LC oscillators. Colpitts oscillators uses capacitive feedback, Hartley oscillator uses inductive feedback.
11․ The following are the necessary requirements of an oscillator
The amplitude and frequency stabilities are the primary requirements for the oscillator which determines the ability to maintain constant amplitude, sustained oscillation and desired frequency of the output waveform.
12․ The Barkhausen criterion for an oscillator
Amplitude of oscillations is decided by unity loop gain and frequency of oscillations is controlled by phase angle. To get sustained oscillation both conditions have to be met. .
13․ LC oscillators are used for produce a waveform with frequency ranging from
LC oscillators are used to produce the output at frequency ranging from 1 MHz to 500MHz that’s why these are also called as RF (radio frequency) oscillators.
14․ Which of the following oscillators are used for low frequency (LF) applications
RC oscillators are used for LF applications because an LC oscillator is difficult to be realized at low frequencies as the size of the inductor required is very large, expensive and bulky.
15․ The expression for frequency of oscillations of a RC phase shift oscillator is
The frequency oscillations of RC phase shift oscillator is as it contains three RC sections.
16․ A diode (P-N junction) has two terminals. The P-terminal is known as
A diode is a semiconductor device which is formed by combining the P-type material and N-type material to diffuse together. P-type material has holes as majority carriers while N-type material has electrons as majority carriers. So, the P-type side is anode and N-type side is cathode.
17․ A working diode must have
A working diode means the diode is biased or connected with the DC source. When a diode is forward biased ( +ve terminal to anode and -ve terminal to cathode ), it provides a low resistance path because it helps the majority carrier to crossover the barrier potential and conduct the flow of current. When a diode is reversed biased ( -ve terminal to anode and +ve terminal to cathode ) it provide a high resistance path because the majority carriers are flows away from the junction and no current conduction takes place.
18․ Electrons in p-type material of a semi-conductor are called as
Electrons in p-type and n-type material of a semi-conductor are called as minority charge carriers and majority charge carriers respectively. Electrons are less in number in the p-type as compared to the holes present in it. So, it is a minority carriers in p-type material.
19․ Silicon and Germanium are ________ elements.
Silicon and Germanium belong to group IVa of the periodic table consisting of four electrons in their valance shell, also called as tetravalant elements. Group IVa elements are Carbon (C) (6) Silicon (Si) (14) (2 8 4) Germanium (Ge) (32) (2 8 18 4) Tin (Sn) (50) Lead (Pb) (82)
20․ A diode (p-n junction) when reverse biased act as
A diode when reverse biased (positive terminal of the battery is connected to cathode and negative terminal of the battery is connected to anode) does not conduct any considerable electric current and hence acts as an off switch.123>>>