A delay-line oscillator is a form of
electronic oscillator 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 A phase-shift oscillator is a linear electronic oscillator circuit that produces a sine wave output. It consists of an inverting amplifier element such as a transistor or op amp with its output fed back to its input through a phase-shift network c ...
in which LC components are lumped, the capacitances and inductances are distributed through the length of the delay line. A
ring oscillator
A ring oscillator is a device composed of an odd number of NOT gates in a ring, whose output oscillates between two voltage levels, representing ''true'' and ''false''. The NOT gates, or inverters, are attached in a chain and the output of the ...
uses a delay line formed from the
gate delay
Propagation delay is the time duration taken for a signal to reach its destination. It can relate to networking, electronics or physics. ''Hold time'' is the minimum interval required for the logic level to remain on the input after triggering ed ...
of 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
Mode ( la, modus meaning "manner, tune, measure, due measure, rhythm, melody") may refer to:
Arts and entertainment
* '' MO''D''E (magazine)'', a defunct U.S. women's fashion magazine
* ''Mode'' magazine, a fictional fashion magazine which is ...
.
The delay-line oscillator may be allowed to ''free run'' or it may be gated for use in
asynchronous logic
Asynchronous circuit (clockless or self-timed circuit) is a sequential digital logic circuit that does not use a global clock circuit or signal generator to synchronize its components. Instead, the components are driven by a handshaking cir ...
.
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 fi ...
can be regarded as a special case of the delay-line oscillator.
See also
*
Opto-electronic oscillator
An opto-electronic oscillator (OEO) is an optoelectronic circuit that produces repetitive electronic sine wave and/or modulated optical continuous wave signals.
An opto-electronic oscillator is based on converting the continuous light energy fr ...
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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