Frequency synthesizer with tunable accuracy
AssigneeIntegrated Device Technology, Inc.
InventorsHui Li, Teck-Chuan Ng, Stephen E. Aycock
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Abstract
An apparatus includes a first circuit, a second circuit and a third circuit. The first circuit may be configured to generate a first code by counting a number of cycles of an input clock signal during a period. The period may be determined by an output clock signal and a second code. The second circuit may be configured to generate a third code by a delta-sigma modulation of the first code. The third circuit may be configured to generate the output clock signal in response to the third code. An accuracy of a frequency of the output clock signal may be determined by a current value of the second code.
Claims20
An apparatus comprising:
- a first circuit configured to generate a first code by counting a number of cycles of an input clock signal during a period, wherein said period is determined by an output clock signal and a second code;
- a second circuit configured to generate a third code by a delta-sigma modulation of said first code, wherein said third code has fewer bits than the first code;
- and
- a third circuit configured to generate an initial frequency said output clock signal in response to said third code, wherein an accuracy of said initial frequency of said output clock signal is adjusted in response to a current value of said second code.
A method for frequency synthesization, comprising the steps of:
- generating a first code using a circuit by counting a number of cycles of an input clock signal during a period, wherein said period is determined by an output clock signal and a second code;
- generating a third code by a delta-sigma modulation of said first code, wherein said third code has fewer bits than the first code;
- and
- generating an initial frequency of said output clock signal in response to said third code, wherein an accuracy of said initial frequency of said output clock signal is adjusted in response to a current value of said second code.
Dependencies are inferred from the claim text.