CET CET Analog Electronics and Amplifiers 2

Question 1

What is the cutoff frequency of a first-order RC low-pass filter with R = 10 kΩ and C = 0.01 µF?

Accepted Answer

1.59 kHz

Answer

f = 1/(2πRC) = 1/(2π × 10,000 × 0.00000001) ≈ 1,592 Hz ≈ 1.59 kHz.

Question 2

An inverting op-amp amplifier has a feedback resistor Rf = 10 kΩ and input resistor Rin = 2 kΩ. What is the closed-loop voltage gain?

Accepted Answer

-5

Answer

Inverting amplifier gain = -Rf/Rin = -10k/2k = -5.

Question 3

Which type of negative feedback increases input impedance and decreases output impedance in an amplifier?

Accepted Answer

Voltage-series (series-shunt) feedback

Answer

Voltage-series (series-shunt) feedback samples the output voltage and applies series feedback at the input, raising Zin and lowering Zout.

Question 4

What does the slew rate of an op-amp specify?

Accepted Answer

The maximum rate of change of output voltage in V/µs

Answer

Slew rate defines the fastest the output voltage can change, expressed in volts per microsecond.

Question 5

Which amplifier class has the highest theoretical DC-to-output efficiency, reaching up to 78.5% for a sinusoidal signal?

Accepted Answer

Class B

Answer

Class B push-pull amplifiers have a theoretical maximum efficiency of 78.5% because each transistor conducts only 180° of the cycle.

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