Active-filter tuned oscillator

An active-filter tuned oscillator is an active electronic circuit designed to produce a periodic signal. It consists of a bandpass filter and an active amplifier, such as an OP-AMP or a BJT. The oscillator is commonly tuned to a specific frequency by varying the reactant of the feedback path within the circuit. An example is the Colpitts oscillator.

Properties

An oscillator is any device or system that produces a periodic output. In a tuned oscillator, the period of the output may be controlled by altering the system's resonant frequency. In the case of a tunable electronic oscillator, this is most commonly achieved by altering the circuit's capacitance.

As with all oscillators, active-filter tuned oscillators adhere to the Barkhausen stability criterion, which states that to maintain oscillation the loop gain must be unity and the phase shift must be 0 or a multiple of 2π.

References

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