Thus Oscillators are self sustaining circuits generating an periodic output waveform at a precise frequency and for any electronic circuit to operate as an oscillator, it must have the following three characteristics.ДЄn oscillator has a small signal feedback amplifier with an open-loop gain equal too or slightly greater than one for oscillations to start but to continue oscillations the average loop gain must return to unity.

In other words, an oscillator is a an amplifier which uses positive feedback that generates an output frequency without the use of an input signal. Oscillators work because they overcome the losses of their feedback resonator circuit either in the form of a capacitor, inductor or both in the same circuit by applying DC energy at the required frequency into this resonator circuit. LC Oscillators are commonly used in radio-frequency circuits because of their good phase noise characteristics and their ease of implementation.ДЄn Oscillator is basically an Amplifier with вЂњPositive FeedbackвЂќ, or regenerative feedback (in-phase) and one of the many problems in electronic circuit design is stopping amplifiers from oscillating while trying to get oscillators to oscillate. Oscillators are used in many pieces of test equipment producing either sinusoidal sine waves, square, sawtooth or triangular shaped waveforms or just a train of repetative pulses of a variable or constant width. This output waveform can have a wide range of different shapes and frequencies, and can be either complex in shape, or be a simple pure sine wave depending upon the application.

Oscillators convert a DC input (the supply voltage) into an AC output (the waveform).

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