Explain the Barkhausen Criterion

Explain the Barkhausen Criterion

Answers

- Barkhausen criterion is that in order to produce continuous undamped oscillations at the output of an amplifier, the positive feedback should be such that:
m_vA_v = 1
- Once this condition is set in the positive feedback amplifier, continuous undamped oscillations can be obtained at the output immediately after connecting the necessary power supplies.

(i) Mathematical explanation: The voltage gain of a positive feedback amplifier is given by;

- We know that we cannot achieve infinite gain in an amplifier. So what does this result infer in physical terms? It means that a vanishing small input voltage would give rise to finite (i.e., a definite amount of) output voltage even when the input signal is zero. Thus once the circuit receives the input trigger, it would become an oscillator, generating oscillations with no external signal source.

(ii) Graphical Explanation. Let us discuss the condition m_vA_v = 1 graphically.

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Wilfykil answered the question on August 15, 2019 at 12:30

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