A low noise amplifier has an effective noise temperature of 50 k. The absolute noise figure is

A low noise amplifier has an effective noise temperature of 50 k. The absolute noise figure is
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A low noise amplifier has an effective noise temperature of 50 k. The absolute noise figure is 1.172

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ECE Board Exam March 1996 The equivalent noise temperature of the amplifier is 25 K. What is the noise figure? A. 1.86 B. 0.1086 C. 1.086 D. 10.86

Description : ECE Board Exam March 1996 The equivalent noise temperature of the amplifier is 25 K. What is the noise figure? A. 1.86 B. 0.1086 C. 1.086 D. 10.86

Last Answer : C. 1.086

Negative feedback amplifier has a signal corrupted by noise as its input. The amplifier will

Description : Negative feedback amplifier has a signal corrupted by noise as its input. The amplifier will   (A) Amplify the noise as much as the signal (B) Reduce the noise (C) Increase the noise (D) Not effect the noise

Last Answer : Negative feedback amplifier has a signal corrupted by noise as its input. The amplifier will Reduce the noise

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

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A receiver connected to an antenna whose resistance is 50 Ω has an equivalent noise resistance of 30Ω. Calculate its equivalent noise temperature if the noise figure is equal to 1.6. A. 17.4 K B. 174K C. 1.74K D. 17K

Description : A receiver connected to an antenna whose resistance is 50 Ω has an equivalent noise resistance of 30Ω. Calculate its equivalent noise temperature if the noise figure is equal to 1.6. A. 17.4 K B. 174K C. 1.74K D. 17K

Last Answer : B. 174K

The main component responsible for the fall of gain of an RC coupled amplifier in low frequency

Description : The main component responsible for the fall of gain of an RC coupled amplifier in low frequency range is  (A) The active device itself (tube, or transistor)  (B) stray shunt capacitance Cs  (C) the grid leak resistance Rg  (D) coupling capacitor Cc

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Calculate the noise figure of the receiver whose RF amplifier has an input resistance of 1000Ω and an equivalent shot-noise resistance of 2000Ω, a gain of 25 and load resistance of 125 kΩ. Given that the bandwidth is 1.0MHz and the temperature is 20˚C, and that the receiver is connected to an antenna with an impedance of 75Ω. A. 30.3 B. 3.03 C. 303 D. .303

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Indicate the false statement. Noise figure is defined as A. the ratio of the S/N power supplied at the input terminal of a receiver or amplifier to the S/N power supplied to the output or load resistor B. noise factor expressed in decibels C. an unwanted form of energy tending to interfere with the proper and easy reception and reproduction of wanted signal D. S/N of an ideal system divided by S/N at the output of the receiver or amplifier under test, both working at the same temperature over the same bandwidth and fed from the same source

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The unity gain bandwidth of an inverting amplifier is 10 MHz What would be the bandwidth if the gain is

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If the feedback factor of an amplifier is 0.1 and its gain without feedback is 40, then its gain with feedback is

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An amplifier operating over the frequency range from 18 to 20 MHz has 10 kilo ohm input resistor. What is

Description : An amplifier operating over the frequency range from 18 to 20 MHz has 10 kilo ohm input resistor. What is the r.m.s. noise voltage at the input to this amplifier if the ambient temperature is 27o C

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For a feedback amplifier, if the loop gain is much greater than unity, the closed loop gain will be equal to

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Description : For Cascode amplifier the output impedance becomes 

Last Answer : For Cascode amplifier the output impedance becomes very high

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An operational amplifier has an open loop gain of 200,000. Its output exhibits saturation at 10V.

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In a radio receiver the IF amplifier

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Class A amplifier is used when

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In an IF amplifier, the IF transformer is provided with tapping to

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In a Klystron amplifier, the RF voltage produces

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ECE Board Exam March 1996 A receiver connected to an antenna whose resistance is 50 ohms has an equivalent noise resistance of 30 ohms. What is the receiver’s noise temperature? A. 754 K B. 464 K C. 174 K D. 293 K

Description : ECE Board Exam March 1996 A receiver connected to an antenna whose resistance is 50 ohms has an equivalent noise resistance of 30 ohms. What is the receiver’s noise temperature? A. 754 K B. 464 K C. 174 K D. 293 K

Last Answer : C. 174 K

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The root mean square speed of molecules of a gas is equal to (where, m = mass of the molecule K = Boltzmann’s constant, T = absolute temperature) (A) √(2KT/m) (B) √(3KT/m) (C) √(6KT/m) (D) 3KT/m

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One of the following is not a useful quantity for comparing the noise performance receivers. A. Input noise voltage B. Equivalent noise resistance C. Noise temperature D. Noise figure.

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Description : The unit of measurement of noise is – (1) Decibel (2) Hertz (3) Amplifier (4) Acoustics

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Which circuit contributes most of the noise in a receiver? A. IF amplifier B. Demodulator C. AF amplifier D. Mixer

Description : Which circuit contributes most of the noise in a receiver? A. IF amplifier B. Demodulator C. AF amplifier D. Mixer

Last Answer : D. Mixer

The noise output of a resistor is amplified by a noiseless amplifier having a gain of 60 and a bandwidth of 20 kHz. A meter connected at the output of the amplifier reads 1mV RMS. If the bandwidth of the amplifier is reduced to 5kHz, its gain remaining constant, what does the meter read now? A. 0.5 mV B. 0.5 µV C. 5.0 mV D. 5.0 µV

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Last Answer : A. 0.5 mV

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

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Last Answer : B. 2,518 Ω

What is the reliable measurement for comparing amplifier noise characteristics? A. Thermal agitation noise B. Noise factor C. Noise margin D. Signal-to-noise

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Last Answer : B. Noise factor

Referred to as the stage in the radio receiver that contributes most of the noise. A. IF amplifier B. Supply stage C. Speaker D. Mixer

Description : Referred to as the stage in the radio receiver that contributes most of the noise. A. IF amplifier B. Supply stage C. Speaker D. Mixer

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