Semiconductors Overview

A collection of a number of energy levels which are closely packed is known as an energy band.

The lower band of solids belongs to the valence electrons is known as the valence band. It may be partially filled or completely filled with electrons.

<p>False</p> Signup and view all the answers

<p>Electrons in the valence band do not gain energy from external electric fields. Hence, the electrons do not contribute to the electric current.</p> Signup and view all the answers

<p>It is situated upper to the valence band in a solid. This band is empty at absolute zero temperature.</p> Signup and view all the answers

<p>False</p> Signup and view all the answers

<p>The distance between the energy level of valence band and lower level of conduction band is called forbidden energy gap.</p> Signup and view all the answers

<p>The energy required to shift electrons from the valence band to the conduction band is called energy band gap (Eg).</p> Signup and view all the answers

<p>The substance having low resistivity or high conductivity is called a conductor.</p> Signup and view all the answers

<p>True</p> Signup and view all the answers

<p>Intrinsic semiconductors are pure semiconductors that have no external impurities.</p> Signup and view all the answers

<p>True</p> Signup and view all the answers

<p>p-type</p> Signup and view all the answers

<p>The semiconductor which is doped with a pentavalent dopant atom is called an n-type semiconductor.</p> Signup and view all the answers

<p>When a p-type semiconductor is suitably connected with n-type semiconductor, then a p-n junction is formed.</p> Signup and view all the answers

<p>When the positive terminal of a battery is connected to the p-type semiconductor and the negative terminal of the battery is connected to the n-type semiconductor, then it is called forward biasing.</p> Signup and view all the answers

<p>When the positive terminal of the battery is connected to the n-type of semiconductor and the negative terminal of the battery is connected to the p-type of semiconductor, then such type of biasing is known as reverse biasing.</p> Signup and view all the answers

<p>Convert AC to DC</p> Signup and view all the answers

<p>Half-wave</p> Signup and view all the answers

<p>It allows only the positive half-cycle of the AC input signal to pass through, while blocking the negative half-cycle.</p> Signup and view all the answers

<p>Rectification efficiency is defined as the ratio of output DC power to the input AC power.</p> Signup and view all the answers

<p>A filter is a circuit that removes the unwanted frequency components from a signal while allowing the desired frequencies to reach the load.</p> Signup and view all the answers

<p>LC filters</p> Signup and view all the answers

<p>A capacitor filter utilizes a capacitor connected in parallel with the load, which acts as a low-impedance path for AC signals while blocking DC signals.</p> Signup and view all the answers

<p>Capacitor filters offer the advantages of low cost, small size, and lightweight, making them ideal for various electronic applications.</p> Signup and view all the answers

<p>An inductor filter uses an inductor connected in series with the load. The inductor acts as a high-impedance path for AC signals, while allowing DC signals to pass through with minimal opposition.</p> Signup and view all the answers

<p>Inductor filters offer advantages such as higher efficiency, lower ripple, and a more robust filtering behavior, particularly for higher AC frequencies.</p> Signup and view all the answers

<p>A zener diode is a heavily doped, properly designed p-n junction diode that exhibits a sharp and well-defined breakdown voltage known as the zener voltage, Vz.</p> Signup and view all the answers

<p>The main function of a zener diode is to regulate voltage, maintaining a stable output voltage across a wide range of input voltages, despite variations in the load.</p> Signup and view all the answers

<p>A solar cell is a p-n junction diode that converts sunlight into electricity.</p> Signup and view all the answers

<p>When sunlight is incident on a solar cell, photons are absorbed by the semiconductor material, leading to the creation of electron-hole pairs. These charge carriers are then separated by the p-n junction, creating a flow of electric current.</p> Signup and view all the answers

<p>A photodiode is a reverse-biased p-n junction diode that exhibits a change in reverse current, proportional to the intensity of light that falls on it.</p> Signup and view all the answers

<p>When a photodiode is reverse-biased and exposed to light, photons incident on the p-n junction generate electron-hole pairs. These charge carriers are then separated by the electric field, leading to an increase in the reverse current, proportional to the intensity of light.</p> Signup and view all the answers

<p>When an LED is forward-biased, electrons from the n-type region recombine with holes in the p-type region, releasing energy in the form of photons, creating visible light.</p> Signup and view all the answers

<p>A transistor is a semiconductor device capable of amplifying and switching electronic signals and electrical power.</p> Signup and view all the answers

<p>Common Base (CB)</p> Signup and view all the answers

<p>Transistor biasing refers to the controlled application of DC voltages to the transistor's terminals to ensure proper operation of the transistor in the active region and to maintain the stability of the functioning circuit.</p> Signup and view all the answers

<p>The stability factor in transistor biasing is a measure of how much the collector current changes with variations in the collector–base leakage current, temperature, and transistor parameters.</p> Signup and view all the answers

<p>Emitter Bias</p> Signup and view all the answers

<p>Fixed bias involves a fixed biasing voltage applied to the base of the transistor through a resistor connected to the base terminal. This configuration provides a simple and straightforward way to set the operating point, but it often lacks good stability.</p> Signup and view all the answers

<p>Voltage divider bias uses a voltage divider network consisting of two resistors connected between the supply voltage and ground to establish a stable biasing voltage for the base.</p> Signup and view all the answers

<p>An operational amplifier, or op-amp, is a high-gain, direct-coupled, differential amplifier, typically implemented as an integrated circuit.</p> Signup and view all the answers

<p>The ideal op-amp is characterized by infinite open-loop gain, infinite input impedance, zero output impedance, and infinite bandwidth.</p> Signup and view all the answers

<p>The virtual ground concept arises in op-amp circuits that use negative feedback. Due to the high open-loop gain of the op-amp, the voltage difference between the inverting input and the non-inverting input is forced to be extremely small.</p> Signup and view all the answers

<p>The open-loop voltage gain (A) of an op-amp is the ratio of the output voltage to the differential input voltage.</p> Signup and view all the answers

<p>Negative feedback in op-amp circuits is used to reduce the overall gain, improve stability, and linearize the amplifier's behavior, making it suitable for a wide range of applications.</p> Signup and view all the answers

<p>CMRR (Common-Mode Rejection Ratio) is a measure of an op-amp's ability to reject common-mode signals, which are signals that are present at both input terminals simultaneously.</p> Signup and view all the answers

<p>The slew rate is the maximum rate of change of the output voltage per unit time.</p> Signup and view all the answers

<p>Virtual ground is a concept that arises in op-amp circuits employing negative feedback. Due to the extremely high open-loop gain of the op-amp, the voltage difference between the inverting input and the non-inverting input is forced to be extremely small.</p> Signup and view all the answers

<p>An inverting amplifier uses negative feedback to amplify the input signal and invert its phase, meaning the output signal is 180 degrees out of phase with the input signal.</p> Signup and view all the answers

<p>An adder circuit uses an op-amp with negative feedback to sum multiple input signals, producing an output signal that is proportional to the sum of the input signals.</p> Signup and view all the answers

<p>A differentiator circuit uses an op-amp with negative feedback to produce an output signal that is proportional to the rate of change of the input signal, effectively performing differentiation.</p> Signup and view all the answers

<p>An integrator circuit uses an op-amp with negative feedback to produce an output signal that is proportional to the integral of the input signal.</p> Signup and view all the answers

<p>A logarithmic amplifier uses a diode and a feedback resistor to produce an output voltage proportional to the logarithm of the input voltage, effectively converting a linear input signal into a logarithmic output signal.</p> Signup and view all the answers

<p>A zero-crossing detector utilizes a comparator circuit to sense when the input signal crosses zero volts and produces a corresponding output, either a high or a low voltage, indicating a change in the input signal's polarity.</p> Signup and view all the answers

<p>A Wien bridge oscillator is a type of electronic oscillator that uses a feedback network to generate a sinusoidal wave signal.</p> Signup and view all the answers

<p>A Wien bridge oscillator consists of an op-amp, a series RC network that determines the oscillation frequency, and a feedback network that provides positive feedback to sustain oscillations.</p> Signup and view all the answers

<p>The Barkhausen criterion is a fundamental principle in electronic oscillators that states that for sustained oscillation, the loop gain of the oscillator must be unity, meaning the product of the open-loop gain (A) and the feedback factor (B) must equal 1.</p> Signup and view all the answers

<p>A Hartley oscillator utilizes a tuned circuit with two inductors connected in series and a capacitor connected in parallel with the inductors. This circuit generates oscillations at a frequency determined by the inductance and capacitance values.</p> Signup and view all the answers

<p>A Colpitts oscillator utilizes a tuned circuit with two capacitors connected in series and an inductor connected in parallel with the capacitors. Oscillations are generated at a frequency determined by the capacitance and inductance values.</p> Signup and view all the answers

<p>The primary difference between Hartley and Colpitts oscillators lies in the configuration of the tuned circuit. Hartley oscillators use two inductors in series and a capacitor in parallel, while Colpitts oscillators use two capacitors in series and an inductor in parallel.</p> Signup and view all the answers

<p>A phase shift oscillator is a type of electronic oscillator that uses a feedback network consisting of a series of RC circuits to generate a sinusoidal wave signal.</p> Signup and view all the answers

<p>RC phase shift oscillators use a chain of three RC circuits, each of which introduces a phase shift of 60 degrees. By connecting these RC circuits in series, a total phase shift of 180 degrees is achieved. The op-amp provides positive feedback to the series RC network, ensuring that the oscillations are sustained and at a frequency determined by the RC components.</p> Signup and view all the answers