Delay-line oscillator

A delay line oscillator is a form of electronic oscillator that uses a delay line as its principal timing element.

By inverting the output of the delay line and feeding that signal back to the input of the delay line, the circuit is caused to oscillate. Properly designed, the simplest style of the circuit will oscillate with a period of two times the delay period of the delay line. By the use of additional taps from the delay line additional outputs can be derived that are correlated in frequency with the main output but vary in phase.

The delay line may be realized with a physical delay line (such as an LC network or a transmission line) or it may be realized using a cascade of logic gates. The timing of a circuit using a physical delay line is usually much more accurate; it is also easier to get such a circuit to oscillate in the desired mode.

The delay line oscillator may be allowed to free run or it may be gated for use in asynchronous logic.

Since the optical cavity is a delay line, a laser can be regarded as a special case of the delay-line oscillator.

A new book contains a comprehensive theoretical and experimental treatise of the delay-line oscillator and of its phase noise and frequency stability. See Chapter 5 of E. Rubiola, Phase Noise and Frequency Stability in Oscillators Cambridge University Press, 2008, ISBN 978-0-521-88677-2.

The author's homepage http://rubiola.org is mostly dedicated to phase noise, frequency stability and oscillators.