Electronics#4: Feedback & Oscillator Circuit

Which of the following improvements is (are) a result of the negative feedback in a circuit?

• Higher input impedance

• Better stabilized voltage gain

• Improved frequency response

• All of the above

Which of the following improvements is (are) a result of the negative feedback in a circuit?

• Lower output impedance

•  Reduced noise

• More linear operation

• All of the above

Which of the following is (are) feedback?

• Voltage-series

• Voltage-shunt

• Current-series

• All of the above

What is the ratio of the input impedance with series feedback to that without feedback?

• 1 + βA

• βA

• β

• 1

What is the ratio of the output impedance with series feedback to that without feedback?

• 1

• 1 + βA

• βA

• A

The frequency distortion arising because of varying amplifier gain with frequency is considerably reduced in a negative-voltage feedback amplifier circuit.

• True

• False

Which of the following is (are) the determining factor(s) of the stability of a feedback amplifier?

• A

• Phase shift between input and output signals

• Both A and the phase shift between input and output signals

• None of the above

At what phase shift is the magnitude of βA at its maximum in the Nyquist plot?

• 90°

• 180°

• 270°

• 0°

At what phase shift is the magnitude of βA at its minimum in the Nyquist plot?

• 90°

• 180°

• 270°

• 0°

The Nyquist plot combines the two Bode plots of gain versus frequency and phase shift versus frequency on a single plot.

• True

• False