Injection locked multi-phase signal generator

Details Injection locked multi-phase signal generator Injection locked multi-phase signal generator

1999-06-30

2001-02-13

Mis, David (Department: 2817)

Oscillators

Polyphase output

C331S047000, C331S055000, C331S057000, C331S172000, C331S175000

Reexamination Certificate

active

06188291

ABSTRACT:

TECHNICAL FIELD
This invention relates to electrical signal generators providing a plurality of equal amplitude periodic output signals which are mutually shifted in phase by 360°
, where n is an integer, particularly a pair of quadrature output signals.
BACKGROUND OF THE INVENTION
Two periodic quadrature signals, typically but not limited to sinusoidal and square wave signals, having equal amplitude but shifted in phase, for example, by one quarter of a period (&pgr;/2) or 90° are required for various types of applications, one of which includes wireless communication systems where quadrature signals are needed, for example, for driving a mixer and where sideband and image suppression depends directly on accuracy of the quadrature phase relationship. Existing techniques for generating quadrature signals utilize, among other things, a phasor sum and difference circuit, a divide-by-two or divide-by-four counter or a combination of R-C low-pass and C-R high-pass filters, possibly connected in a feedback loop. Currently, none of these approaches has been found to be entirely satisfactory in terms of quadrature accuracy, power dissipation and/or phase noise.
SUMMARY OF THE INVENTION
The foregoing deficiencies are overcome in accordance with the principles of the invention by generating one or more pairs of periodic extremely phase accurate output signals of equal amplitude by injection locking a ring oscillator with a multi-phase signal generator which generates a first set of phase related output signals. Injection locking refers to the coupling of a signal from an outside source into an oscillator for improving the frequency or phase difference stability of the output signal generated by the oscillator. The multi-phase signal generator is driven by a low phase noise signal source which generates an output signal which meets, for example, a well known noise standard.
In another embodiment, a first multi-stage (even or odd numbered) ring oscillator is injection locked to a low-phase noise oscillator having a predetermined noise specification which is application specific. A second multi-stage differential ring oscillator identical to the first ring oscillator within manufacturing tolerances is coupled to the first ring oscillator and is injection locked thereby so as to generate a plurality of multi-phase outputs which are mutually shifted in phase by an integer fraction phase increment of 360°, i.e., 360°
where n is an integer, and which provide an improvement in the accuracy of the mutual phase difference over the accuracy of the mutual phase difference of the first ring oscillator and which are, furthermore, insensitive to harmonic distortion in the driving signal. The process of injection locking is relatively fast which results in the reduction of phase noise or “jitter” over a large bandwidth.


REFERENCES:
patent: 5357217 (1994-10-01), Marchesi et al.
patent: 5563554 (1996-10-01), Mizuno
patent: 5581215 (1996-12-01), Ogasawara
patent: 5592127 (1997-01-01), Mizuno
patent: 5635877 (1997-06-01), Monk et al.
patent: 5677650 (1997-10-01), Kwasniewski et al.
patent: 5864258 (1999-01-01), Cusinato et al.
“Fundamental Consideration Of The Stabilization Of an Oscillator By Injection Locking”, Electronics and Communications in Japan, vol. 52-B, No. 4, 1969, pp. 73-80; Saito et al.

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