Velio Communications, Inc.

Rambus Inc.

Xiaoying Yu

William James Dally

John Wood Poulton

Ramin Farjad-Rad

Teva J Stone

A phase comparison of timing signals is made by combinational circuitry which receives the timing signals and a window signal, the window signal identifying edges of the timing signals to be compared. The comparison may result in a charge pumped output which can be fed back to control the phase of one of the timing signals. The phase comparator and charge pump circuit can be included in a multiplier circuitry in which the phase of an input signal is directly compared to the phase of an edge of the multiplied signal.

Combined phase comparator and charge pump circuit

Frequency multiplier with phase comparator

The timing circuit includes at least one delay element and its supply voltage is obtained from an active current source. The current source is a current mirror which is driven by a differential amplifier. The differential amplifier compares a voltage on the delay element supply line to a voltage on a current control node connected to a voltage controlled current source. An RC compensating circuit may be coupled to the current control node.

Low-power low-jitter variable delay timing circuit

The timing circuit includes at least one delay element and its supply voltage is obtained from an active current source. The current source is a current mirror which is driven by a differential amplifier. The differential amplifier compares a voltage on the delay clement supply line to a voltage on a current control node connected to a voltage controlled current source. An RC compensating circuit may be coupled to the current control node.

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Milpitas, CA, United States of America

Xiaoying Yu