Q1Analog Electronics
Question
3 marks
(a) What is an oscillator? How it is differ from an amplifier?
Answer
An oscillator is a circuit that generates a continuous, periodic waveform without any external AC input, unlike an amplifier which requires an input signal and only magnifies it.
An oscillator is an electronic circuit that converts DC power supply energy into a periodic AC output signal (sine wave, square wave, etc.) without requiring any external AC input signal. It is a self-sustaining source of alternating signal.
- Input: An amplifier requires an external AC input signal; an oscillator does not require any input signal.
- Feedback: An oscillator uses positive (regenerative) feedback; an amplifier typically uses negative feedback for stability.
- Output: An oscillator produces its own continuous output; an amplifier produces a larger replica of the input signal.
- Barkhausen Criterion: For an oscillator, the loop gain must be and total phase shift = 0° or 360°; this condition does not apply to amplifiers.
- Energy Source: Oscillator derives output energy from the DC supply; amplifier draws extra energy from supply proportional to input.