Phase Shift Oscillator | Circuit Diagram | Working Principle | New Topic [2023]

Welcome to Poly Notes Hub, In this note we are discussing the Phase Shift Oscillator, its Circuit Diagram, Working Principle, and Advantages and Disadvantages.

Author Name: Arun Paul.

About Phase Shift Oscillator

Fig shows the circuit of a phase shift oscillator. It comprises a conventional signal transistor amplifier and a RC phase shift network. The phase shift network consists of three sections R₁C₁, R₂C₂, and R₃C₃. At some particular frequency f0, the phase shift in each RC section is 60°, so the total phase shift produced by the RC network is 180°. The frequency of Oscillations is given by:

f = 1⁄(2πRC√6) ——— (i)

Where,

R₁ = R₂ = R₃ = R

C₁ = C₂ = C₃ = C

Operation of Phase Shift Oscillator

When the circuit is switched on, it produces oscillations of frequency determined by exp (i). The output E0 of the amplifier is fed back to the RC feedback network. This network produces a phase shift of 180° and a voltage Ei appears at its output which is applied to the transistor amplifier.

The feedback fraction m=Ei/E0. The feedback phase is correct. The transistor amplifier produces a phase shift of 180°. The RC network produces a further phase shift of 180°. As a result, the phase shift around the entire loop is 360°.

Advantages of Phase Shift Oscillator

1. It does not require transformers or inductors.
2. It can be used to produce very low frequencies.
3. The circuit provides good frequency stability.

Disadvantages of Phase Shift Oscillator

1. )It is difficult for the circuit to start oscillations as the feedback is generally small.
2. The circuit gives small output.

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