N-way circular phase interpolator for generating a signal having arbitrary phase
First Claim
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1. A circular phase interpolator for generating a clock having a phase and comprising:
- a multiplexer for receiving a plurality of signals representative of evenly spaced phases of a reference clock and in response thereto supplying at least three input phases;
input ports for receiving the at least three input phases each phase being representative of a different one of the phases of the reference clock;
input ports for receiving at least three input weight signals; and
circuitry for applying each of the at least three input weight signals to a different one of the at least three input phases thereby forming a weighted sum of the at least three input phases, which sum represents the phase of the generated clock.
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Abstract
An N-way Circular Phase Interpolator interpolates the N phases of a reference clock signal to generate a tunable clock. By using more than two phases for interpolation, high excess frequencies as well as high precision (i.e. small jitter) are achieved. The N-way Circular Phase Interpolator provides for analog filtering in the phase domain, which attenuates the out-of-band phase noises thus further reducing the output jitter.
72 Citations
24 Claims
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1. A circular phase interpolator for generating a clock having a phase and comprising:
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a multiplexer for receiving a plurality of signals representative of evenly spaced phases of a reference clock and in response thereto supplying at least three input phases;
input ports for receiving the at least three input phases each phase being representative of a different one of the phases of the reference clock;
input ports for receiving at least three input weight signals; and
circuitry for applying each of the at least three input weight signals to a different one of the at least three input phases thereby forming a weighted sum of the at least three input phases, which sum represents the phase of the generated clock. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method for generating a clock having a phase, said method comprising:
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receiving a plurality of evenly spaced phases of a reference clock;
receiving a plurality of control signals;
choosing at least three input phases from the plurality of evenly spaced phases of the reference clock based on the control signals;
supplying the at least three input phases;
receiving the at least three input phases, each phase being representative of a different one of phases of the reference clock;
receiving at least three input weight signals; and
applying each of the at least three input weight signals to a different one of the at least three input phases thereby forming a weighted sum of the at least three input phases, which sum represents the phase of the generated clock. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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Specification