Define the term related to power amplifier. (i) Efficiency (ii) Voltage gain

Define the term related to power amplifier. (i) Efficiency (ii) Voltage gain
by

1 Answer

Answer :

(i) Efficiency: Efficiency of the power amplifier is defined as the ratio of maximum a.c. output power to the d.c. input power. Mathematically

image

(ii) Voltage gain: Voltage gain of the power amplifier is defined as the ratio of output voltage to the input voltage. Mathematically,

image

by

Related questions

With the help of neat circuit diagram, explain the operation of voltage shunt type feedback amplifier.

Description : With the help of neat circuit diagram, explain the operation of voltage shunt type feedback amplifier.

Last Answer : Diagram:  Fig. shows common emitter transistor amplifier with a feedback resistor RF connected between its output and input terminals. This is collector to base biasing when the input signal is ... As IS = If + Ii it is shunt type therefore it voltage shunt negative feedback amplifier.

Compare Class A ,Class B, Class C and class AB power amplifiers on the basis of: i)Angle of conduction ii)Efficiency iii)Position of operating pointing power dissipation iv)Distortion

Description : Compare Class A ,Class B, Class C and class AB power amplifiers on the basis of: i)Angle of conduction ii)Efficiency iii)Position of operating pointing power dissipation iv)Distortion

Last Answer : Compare Class A ,Class B, Class C and class AB power amplifiers on the basis of: i)Angle of conduction ii)Efficiency iii)Position of operating pointing power dissipation iv)Distortion

Explain with circuit diagram and waveform the operation of class AB push pull power amplifier.

Description : Explain with circuit diagram and waveform the operation of class AB push pull power amplifier.

Last Answer : Class AB Push Pull Power Amplifier:  Circuit Diagram:  Circuit Decription: The circuit consists of two centre-tapped transformers T1 and T2, two identical transistors Q1 and Q2 , Resistor R and ... two halves & produces a full sine wave in the load resistor. Waveform :

Draw the circuit diagram of class AB power amplifier and describe its working.

Description : Draw the circuit diagram of class AB power amplifier and describe its working.

Last Answer : Circuit diagram: Circuit Description: The circuit consists of two center-tapped transformers T1 and T2, two identical transistors Q1 and Q2 , Resistor R and diode D. The DC voltage ... and Q2 conduct, as soon as input cross zero, negative sinusoidal voltage will appear across load.

Describe the operation of class-C type of power amplifier with the help of neat sketch.

Description : Describe the operation of class-C type of power amplifier with the help of neat sketch.

Last Answer : Circuit diagram: Operation: * Class C power amplifier is a type of amplifier where the transistor conducts for less than one half cycle of the input signal. Less than one ... resonant circuit oscillates in one frequency (generally the carrier frequency) all other frequencies are attenuated. 

Compare small signal amplifier with power amplifier

Description : Compare small signal amplifier with power amplifier

Last Answer : Parameters Small signal Amplifiers Power Amplifiers Amplification quantity It increases voltage into high resistance load. Hence small signal amplifiers are also called as voltage amplifiers. It ... Coupling R-C coupling Transformer coupling Power output low High

Comment on the effect of negative feedback on the gain, input and output resistance of the feedback amplifiers.Describe the gain bandwidth product term used in this context and its importance.

Description : Comment on the effect of negative feedback on the gain, input and output resistance of the feedback amplifiers.Describe the gain bandwidth product term used in this context and its importance.

Last Answer : Effect of negative feedback: 1. Gain decreases with negative feedback. 2. Input resistance increases with negative feedback. 3. Output resistance decreases with negative feedback. Explanation ... feedback bandwidth increases which means it is stable output on more range of frequency.

Draw the circuit of complementary, symmetry push pull amplifier and explain its working.

Description : Draw the circuit of complementary, symmetry push pull amplifier and explain its working.

Last Answer : COMPLEMENTRY SYMMETRY CLASS B PUSH PULL AMPLIFIER  Circuit Diagram:  Circuit description: * Two transistors one NPN & other PNP is used in the circuit so they are complementary to each other. ... conducts & NPN remains OFF.  So we get remaining half cycle in the output.

Explain stagger tuned amplifier with the help of waveforms.

Description : Explain stagger tuned amplifier with the help of waveforms.

Last Answer : Circuit Diagram: Above figure shows two-stage tuned voltage amplifier. The stagger tuning in this circuit, may be achieved by resonating the tuned circuits L1C1 and L2C2 to slightly different ... outside the pass-band. Because of the stagger tuning there is a loss of voltage gain.

Sketch circuit diagram of common source FET Amplifier. State working principle of it.

Description : Sketch circuit diagram of common source FET Amplifier. State working principle of it.

Last Answer : Working: -  * When small a.c. signal is applied to the gate, it produces variation in the gate to source voltage. This produces variation in the drain current. As the gate to source ... and we get amplification. Thus the AC output voltage VDS is 180º out of phase with AC input voltage.

Explain principle of feedback amplifier.

Description : Explain principle of feedback amplifier.

Last Answer : Block diagram of feedback amplifier:- Explanation:- * Feedback is a process of injecting some energy from the output and then it back to the input. The amplifier which use the feedback principle are ... Now, The quantity β = Vf /Vo is called as feedback ratio or feedback fraction.

Describe the operation of double tuned amplifier with the help of neat circuit diagram and mention its applications.

Description : Describe the operation of double tuned amplifier with the help of neat circuit diagram and mention its applications.

Last Answer : Circuit diagram: Operation:  *The signal to be amplified is applied at the input terminal through the coupling capacitor CC  *The resonant frequency of the tuned circuit L1 C1 is made equal ... : (i) Radio and T .V broadcasting as tuning circuit. (ii) Wireless communication system.

State the need of tuned amplifier in electronic circuits.

Description : State the need of tuned amplifier in electronic circuits.

Last Answer : Necessity of tuned amplifier: 1. Selection of the desired radio frequency signal. 2. Amplification of the selected signal to a selected voltage level.

State advantages of negative feedback used in feedback amplifier.

Description : State advantages of negative feedback used in feedback amplifier.

Last Answer : Advantage of negative feedback amplifier: * Increased stability in gain * Increased bandwidth * Less amplitude and harmonic distortion * Decreased noise * Less frequency distortion * Less non-linear distortion * Input and output resistance can be modified as desired

List the types of coupling used in BJT amplifier.

Description : List the types of coupling used in BJT amplifier. 

Last Answer : Types of coupling used in BJT amplifier: i. Resistance capacitance (RC)coupling ii. Impedance coupling iii. Transformer coupling iv. Direct coupling

Define : (i) Sweep time (ii) Retrace time

Description : Define : (i) Sweep time (ii) Retrace time

Last Answer : (i) Sweep time: It is defined as time interval taken by time based signal generator to increase from minimum to maximum voltage. (ii) Retrace time: It is defined as time taken by time based signal generator to decrease from maximum to minimum voltage.

Compare between class A and class B amplifier on the basis of (i) Efficiency (ii) Power (iii) Position of Q- point (iv) O/P distortion

Description : Compare between class A and class B amplifier on the basis of (i) Efficiency (ii) Power (iii) Position of Q- point (iv) O/P distortion

Last Answer : Parameter Class A Class B 

Define the following terms related to antennas; (i) Antenna resistance (ii) Directivity (iii) Antenna gain (iv) Power density

Description : Define the following terms related to antennas; (i) Antenna resistance (ii) Directivity (iii) Antenna gain (iv) Power density

Last Answer : Antenna Resistance - The resistance of an antenna has two components: 1. Its radiation resistance due to conversion of power into electromagnetic waves 2. The resistance due to actual losses in the ... the transmitter power divided by the surface area of a sphere (4πR2) at that distance.

Compare the fixed voltage regulators using 78XX and 79XX.

Description : Compare the fixed voltage regulators using 78XX and 79XX.

Last Answer : Compare the fixed voltage regulators using 78XX and 79XX.

A final amplifier of a radio transmitter draws 250 mA of plate current when the plate supply voltage is 1400 volts. If the plate circuit efficiency is 80% and the transmitter is connected to an antenna having a feed impedance of 70 ohms, what is the antenna current at the feed-point? A. 4.0 A B. 2.2 A C. 1.25 A D. 2.0 A

Description : A final amplifier of a radio transmitter draws 250 mA of plate current when the plate supply voltage is 1400 volts. If the plate circuit efficiency is 80% and the transmitter is connected to an antenna having a feed impedance of 70 ohms, ... at the feed-point? A. 4.0 A B. 2.2 A C. 1.25 A D. 2.0 A

Last Answer : D. 2.0 A

When troubleshooting an amplifier, you measure an output of 30 volts. If the gain of the amplifier is 2, what must the input voltage be for the amplifier to work properly? A. 32 volts B. 30 volts C. 28 volts D. 15 volts

Description : When troubleshooting an amplifier, you measure an output of 30 volts. If the gain of the amplifier is 2, what must the input voltage be for the amplifier to work properly? A. 32 volts B. 30 volts C. 28 volts D. 15 volts

Last Answer : Answer: D

The first stage of a two-stage amplifier has a voltage gain of 10, a 600 Ω input resistor, a 1600Ω equivalent noise resistance and 27kΩ output resistor. For the second stage, these values are 25, 81kΩ, 19kΩ, and 1MΩ, respectively. Calculate the equivalent input-noise resistance of this two stage amplifier. A. 2,518 kΩ B. 2,518 Ω C. 251.8 Ω D. 12,518 Ω

Description : The first stage of a two-stage amplifier has a voltage gain of 10, a 600 Ω input resistor, a 1600Ω equivalent noise resistance and 27kΩ output resistor. For the second stage, these values are 25, 81kΩ, 19kΩ, and 1MΩ, ... this two stage amplifier. A. 2,518 kΩ B. 2,518 Ω C. 251.8 Ω D. 12,518 Ω

Last Answer : B. 2,518 Ω

A certain common-emitter amplifier has a voltage gain of 100. If the emitter bypass capacitor is removed.

Description : A certain common-emitter amplifier has a voltage gain of 100. If the emitter bypass capacitor is removed.  a. The circuit will become unstable b. The voltage gain will decrease  c. The voltage gain will increase d. The circuit will become stable

Last Answer : B

An amplifier without feedback has a voltage gain of 50, input resistance 1kΩ and output resistance of 2.5kΩ.

Description : An amplifier without feedback has a voltage gain of 50, input resistance 1kΩ and output resistance of 2.5kΩ. The input resistance of the current-shunt negative feedback amplifier using the above amplifier with a feedback factor of 0.2 would be: (1) 1/11 kΩ (2) 1/5 kΩ (3) 5 kΩ (4) 11 kΩ

Last Answer : An amplifier without feedback has a voltage gain of 50, input resistance 1kΩ and output resistance of 2.5kΩ. The input resistance of the current-shunt negative feedback amplifier using the above amplifier with a feedback factor of 0.2 would be: 1/11 kΩ

The voltage gain of a common base amplifier depends on

Description : The voltage gain of a common base amplifier depends on  1. Load resistor RL 2. input resistance of transistor 3. Ac alpha 4. All the above 

Last Answer : The voltage gain of a common base amplifier depends on  1. Load resistor RL 2. input resistance of transistor 3. Ac alpha 4. All the above 

An amplifier has a voltage gain of 120. To reduce distortion, 10% negative feedback is employed. The gain of

Description : An amplifier has a voltage gain of 120. To reduce distortion, 10% negative feedback is employed. The gain of the amplifier with feedback is  (1) 141 (2) 92.3 (3) 9.23 (4) 1.41

Last Answer : An amplifier has a voltage gain of 120. To reduce distortion, 10% negative feedback is employed. The gain of the amplifier with feedback is 9.23

The voltage gain of a common -source JFET amplifier depends up on its

Description : The voltage gain of a common -source JFET amplifier depends up on its  (1) Input impedance (2) Amplification factor (3) Dynamic drain resistance (4) Drain load resistance

Last Answer : B

An amplifier has a voltage gain of 50; this gain in dB will be

Description : An amplifier has a voltage gain of 50; this gain in dB will be (A) 34 dB (B) 68 dB (C) 41 dB (D) 14 dB 

Last Answer : An amplifier has a voltage gain of 50; this gain in dB will be 34 dB

In a differential amplifier the differential voltage gain is 500 and the common mode voltage gain is 0.5. ...

Description : In a differential amplifier the differential voltage gain is 500 and the common mode voltage gain is 0.5. The CMRR in dB is (a) 80 (b) 60 (c) 30 (d) 20

Last Answer : Ad - differential voltage gain. Acm- common mode voltage gain CMRR - common mode rejection ratio  CMRR = 20log(Ad/Acm) = 60 dB

The closed-loop voltage gain of an inverting amplifier equal to

Last Answer : The closed-loop voltage gain of an inverting amplifier equal to The feedback resistance divided by the input resistance.

Explain the term crossover distortion. State methods to overcome it.

Description : Explain the term crossover distortion. State methods to overcome it.

Last Answer : Explanation:-  * Cross over distortion occurs in Class B push pull Amplifier.  * In the push-pull configuration, the two identical transistors get into conduction, one after the other and the output ... transistors won t be OFF at the same time. The remedy is to use Class AB amplifier.

Define gain and bandwidth of an amplifier.

Description : Define gain and bandwidth of an amplifier.

Last Answer : Bandwidth  The range of frequency over which the voltage gain is equal to or greater than 70.7% of its maximum value Gain: The ratio of output parameter (voltage/ current /power) to the input parameter (voltage/ current /power) of an amplifier is known as gain. It is denoted by a letter A

Define: (i) Efficiency (ii) Voltage regulation of transformer.

Description : Define: (i) Efficiency (ii) Voltage regulation of transformer.

Last Answer : i) Efficiency : It is the ratio of output power to the input power of the transformer.It is denoted by η. ii) Voltage Regulation of transformer: The ratio of the change in Secondary Terminal ... So where, VNL = No Load Secondary voltage VFL = Full load secondary voltage

Define following parameter of rectifier: (i) Ripple factor (ii) Efficiency (iii) Peak Inverse Voltage (iv) Transformer utilization factor

Description : Define following parameter of rectifier: (i) Ripple factor (ii) Efficiency (iii) Peak Inverse Voltage (iv) Transformer utilization factor

Last Answer : (i) Ripple Factor - Ripple factor (γ) may be defined as the ratio of the root mean square (rms) value of the ripple voltage to the absolute value of the DC component of the ... the same rectifier. Effective VA Rating of transformer is the average of primary and secondary VA rating of transformer.

Define each of following terms of operational amplifiers i) Slew rate ii) Input offset voltage iii) Voltage gain iv) Input capacitance

Description : Define each of following terms of operational amplifiers i) Slew rate ii) Input offset voltage iii) Voltage gain iv) Input capacitance

Last Answer : i) Slew rate:- Maximum rate of change of o/p voltage per unit of time. It is express in volt/µsec.  ii) Input offset voltage:- The voltage that must be applied between two ... capacitance that can be measured at either be inverting or non-inverting terminal with other terminal connected to ground.

Classify the power amplifiers on the basis of operation and input/output waveforms.

Description : Classify the power amplifiers on the basis of operation and input/output waveforms.

Last Answer : Depending upon the operation and input/output waveforms power amplifiers are classified into following type. 1) Class A amplifier. 2) Class B amplifier. 3) Class C amplifier. 4) Class AB amplifier. 5) Class D amplifier

Which power amplifier has maximum efficiency?

Description : Which power amplifier has maximum efficiency? A. Class B B. Class C C. Class A D. all are equally efficient

Last Answer : Class B power amplifier has maximum efficiency.

Define the percentage voltage regulation and efficiency of a power transformer.

Description : Define the percentage voltage regulation and efficiency of a power transformer.  

Last Answer : Voltage regulation is the difference between no load voltage and full load voltage by no load voltage. Voltage regulation = No load voltage - Full load voltage / No load voltage. Voltage regulation is mentioned ... . % Efficiency = Output in watts * 100 / Output in watts + losses. 

Basic operating characteristics of the operational amplifier such as gain and stability are the function of its _____________. A. differential input stage B. power output stage C. feedback circuit D. supply voltages

Description : Basic operating characteristics of the operational amplifier such as gain and stability are the function of its _____________. A. differential input stage B. power output stage C. feedback circuit D. supply voltages

Last Answer : Answer: C

What is meant by antenna gain? A. The final amplifier gain minus the transmission line losses (including any phasing lines present) B. The ratio of the amount of power produced by the antenna compared to the output power of the transmitter C. The ratio of the signal in the backward direction D. The numeric ratio relating the radiated signal strength of an antenna to that of another antenna

Description : What is meant by antenna gain? A. The final amplifier gain minus the transmission line losses (including any phasing lines present) B. The ratio of the amount of power produced by the antenna ... D. The numeric ratio relating the radiated signal strength of an antenna to that of another antenna

Last Answer : D. The numeric ratio relating the radiated signal strength of an antenna to that of another antenna

The operational amplifier is _______ (a) High gain amplifier (b) high power amplifier (c)high resistance amplifier (d)low resistance amplifier

Description : The operational amplifier is _______ (a) High gain amplifier (b) high power amplifier (c)high resistance amplifier (d)low resistance amplifier

Last Answer : a) High gain amplifier

An amplifier has input power of 2 microwatts. The power gain of the amplifier is 60 dB. The output power will be

Description : An amplifier has input power of 2 microwatts. The power gain of the amplifier is 60 dB. The output power will be

Last Answer : An amplifier has input power of 2 microwatts. The power gain of the amplifier is 60 dB. The output power will be 2 watts

Draw Bootstrap sweep generator circuit. Compare Miller Integrator and bootstrap sweep generator with respect to the technique used.

Description : Draw Bootstrap sweep generator circuit. Compare Miller Integrator and bootstrap sweep generator with respect to the technique used.

Last Answer : Circuit diagram of bootstrap sweep generator: Miller Integrator Bootstrap sweep generator It is an integrator used to convert input step waveform into ramp waveform. In ... than Bootstrap sweep circuit The linearity of sweep voltage is poor than Miller integrator

State classification of Amplifiers.

Description : State classification of Amplifiers.

Last Answer : CLASSIFICATION OF AMPLIFIERS: A] Based on input signal 1. Small signal amplifiers 2. Large signal amplifiers B] Based on output signal 1. Voltage amplifier 2. Power amplifier C ... coupling 1. Direct coupled amplifiers 2. R-C Coupled amplifier 3. Transformer coupled amplifier

Compare between RC phase shift oscillator and crystal oscillator.

Description : Compare between RC phase shift oscillator and crystal oscillator.

Last Answer : RC phase shift oscillator Crystal oscillator This oscillator is used for low frequency range. Quartz crystal is mainly used in radio-frequency (RF) oscillators Used resistor and capacitor ... RC network is used as feedback network. Crystal is connected in feedback.

Justify the need of current time base generator to obtain the specified sawtooth waveform with one example.

Description : Justify the need of current time base generator to obtain the specified sawtooth waveform with one example.

Last Answer : Justification:- * Current Time base generator is a circuit where the output current is a linear function of time over a specified time interval. * Time base circuits are used by radar systems to determine ... the time. * The diode D does not conduct during the sweep, because it is reverse biased.

_____ of an antenna is a measure of how the antenna concentrates its radiated power in a given direction. A. Efficiency B. Power C. Gain D. Polarization

Description : _____ of an antenna is a measure of how the antenna concentrates its radiated power in a given direction. A. Efficiency B. Power C. Gain D. Polarization

Last Answer : C. Gain

An increase in the effective power radiated by an antenna in a certain desired direction at the expense of power radiated in other directions. A. Antenna gain B. Antenna back lobe ration C. Antenna total ration D. Antenna efficiency

Description : An increase in the effective power radiated by an antenna in a certain desired direction at the expense of power radiated in other directions. A. Antenna gain B. Antenna back lobe ration C. Antenna total ration D. Antenna efficiency

Last Answer : A. Antenna gain

It is the same with directive gain except that the total power fed to the antenna is used and the antenna efficiency is taken into account.

Description : It is the same with directive gain except that the total power fed to the antenna is used and the antenna efficiency is taken into account.

Last Answer : power gain

An antenna has a radiation resistance of 72 Ω a loss resistance of 8 Ω and a power gain of 16. Find efficiency and directivity.

Description : An antenna has a radiation resistance of 72 Ω a loss resistance of 8 Ω and a power gain of 16. Find efficiency and directivity.

Last Answer : An antenna has a radiation resistance of 72 Ω a loss resistance of 8 Ω and a power gain of 16. Find efficiency and directivity.