Electrical transmission or interconnection systems – Nonlinear reactor systems – Parametrons
Patent
1987-11-17
1989-09-19
Miller, Stanley D.
Electrical transmission or interconnection systems
Nonlinear reactor systems
Parametrons
328 55, 328134, 307511, 307525, 307269, 307603, 331 25, 331 51, 331DIG2, H03K 513, H03K 5159, H03K 1728, H03L 700
Patent
active
048685143
ABSTRACT:
This disclosure concerns digital correction of oscillator drift by providing phase alignment between two clock signals running at nearly the same frequency. Phase alignment is provided by fashioning a delay for one of the clock signals through selection of various lengths of a variable delay path formed from a series of logic circuits. Respective reference signals are derived from the two clocks to be phase-aligned, and the phases of the references are compared in a digital phase comparator. The product of phase comparison controls a digital delay selector to generate a sequence of delay signals corresponding to a sequence of detected phase differences. The delay signal sequence controls the variable digital delay. The variable digital delay outputs a corrected clock signal whose phase is aligned with the phase of the other clock signals. The corrected clock signal is used to produce one reference signal, the other reference signal being derived directly from the other clock signal. A second digital phase comparator compares the phase of the corrected clock signal with a predetermined reference phase of the clock signal from which it is derived. When the phases of the clocks are aligned, the second comparator produces a reset signal which resets the digital selection circuit to a predetermined point in the delay signal sequence, thereby operating the variable digital delay to correct the clock signal to a phase corresponding to the predetermined reference phase.
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Azevedo Michael J.
Corchero Charles A.
Lang Donald J.
Woodman, Jr. Gilbert R.
International Business Machines - Corporation
Mai Huy Kim
Miller Stanley D.
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