A delay-line oscillator is a form of
electronic oscillator
An electronic oscillator is an electronic circuit that produces a periodic, oscillating electronic signal, often a sine wave or a square wave or a triangle wave. Oscillators convert direct current (DC) from a power supply to an alternating cur ...
that uses a
delay line as its principal timing element.
The circuit is set to oscillate by
inverting the output of the delay line and feeding that signal back to the input of the delay line with appropriate amplification. The simplest style of delay-line oscillator, when properly designed, will oscillate with period exactly two times the delay period of the delay line. Additional outputs that are correlated in frequency with the main output but vary in phase can be derived by using additional taps from within the delay line.
The delay line may be realized with a physical delay line (such as an
LC network or a
transmission line
In electrical engineering, a transmission line is a specialized cable or other structure designed to conduct electromagnetic waves in a contained manner. The term applies when the conductors are long enough that the wave nature of the transmi ...
). In contrast to a
Phase-shift oscillator in which LC components are lumped, the capacitances and inductances are distributed through the length of the delay line. A
ring oscillator uses a delay line formed from the
gate delay of a cascade of
logic gate
A logic gate is an idealized or physical device implementing a Boolean function, a logical operation performed on one or more binary inputs that produces a single binary output. Depending on the context, the term may refer to an ideal logic ga ...
s. 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
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The word "laser" is an acronym for "light amplification by stimulated emission of radiation". The firs ...
can be regarded as a special case of the delay-line oscillator.
See also
*
Opto-electronic oscillator
References
* Silicon-Based Distributed Voltage-Controlled Oscillators, IEEE Journal of Solid-State Circuits, Vol. 36 No. 3, March 2001, pp 493-502.
* Design of a CMOS 12 GHz Rotary Travelling Wave Oscillator with Switched Capacitor Tuning, IEEE Radio Frequency Integrated Circuits Symposium, 2009.
Electronic oscillators
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