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251.

An exponential amplifier has diode in feedback path.

Answer» It has resistance in feedback path.
Discussion
252.

DC amplifiers have a tendency to be unstable.

Answer» Due to drift.
Discussion
253.

A half wave diode rectifier has a capacitance input filter. If input voltage is V sin ω, PIV is

Answer» Because capacitor charge is retained.
Discussion
254.

An amplifier with loop gain Aβ will be more stable for value of Aβ as

Answer» A feedback amplifier is stable if loop gain is less than unity. More less, more stable, hence β will be more stable.
Discussion
255.

In a circuit of figure, V = 10 cos(ω) power drawn by the 2Ω resistor is 4 watts. The power factor is

Answer» Vs = 10 cos ωt, Let I be the current, then P = I2 R I is the rms current. Prms = I2 R 4 I2 = 4 I = 2A. Total power drawn = Vm Im cos θ 10 x 2 cos θ = 10 cos θ Total power cannot be determine until value of R = 12 Ω is given.
Discussion
256.

The quiescent collector current I, and collector to emitter voltage V in a CE connection are the values when

Answer» Quiescent-operation means operation when ac signal is not applied.
Discussion
257.

In the op-amp circuit of figure, V =

Answer» .
Discussion
258.

Figure shows the self bias circuit for CE amplifier and its equivalent circuit. V and R respectively are

Answer» .
Discussion
259.

An RC coupled amplifier has an open loop gain of 200 and a lower cutoff frequency of 50 Hz. If negative feedback with β = 0.1 is used, the lower cut off frequency will be

Answer» New lower cutoff frequency = .
Discussion
260.

In figure = 8 V and = 4 V. Which diode will conduct?

Answer» D1 will conduct and the output voltage will be about 7 V. Therefore D2 will be reverse biased and will not conduct.
Discussion
261.

The load impedance Z of a CE amplifier has R and L in series. The phase difference between output and input will be

Answer» It is 180° for purely resistive load and between 180° and 270° for R-L load.
Discussion
262.

Gain of the amplifier is 'A'. Then the I/P impedance and O/P impedance of the closed loop amplifier shown below would be

Answer» By using Miller theorem circuit can be redrawn as .
Discussion
263.

If an amplifier with gain of - 1000 and feedback factor β = - 0.1 had a gain change of 20% due to temperature, the change in gain of the feedback amplifier would be

Answer» As we know, Gain with feedback A = - 1000, β = -0.1 .
Discussion
264.

A half wave diode circuit using ideal diode has an input voltage 20 sin ω volts. Then average and rms values of output voltage are

Answer» and VC = 0.5 x 20 = 10 V.
Discussion