Circuit and method for controlling a spread spectrum transition
AssigneeCypress Semiconductor Corporation
InventorsI-Teh Sha, Kuang-Yu Chen, Albert Chen
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Abstract
A circuit and method for controlling a spread spectrum transition are presented comprising a first circuit and a second circuit. The first circuit may be configured to generate a clock signal in response to (i) a reference signal, (ii) a sequence of spread spectrum ROM codes, and (iii) a command signal. The second circuit may be configured to synchronize the command signal to a feedback signal. The sequence of spread spectrum ROM codes may be generated according to a predetermined mathematical formula and optimized in accordance with predetermined criteria.
Claims23
A spread spectrum clock generator circuit comprising:
- a first circuit configured to generate a clock signal in response to (i) a reference signal, (ii) a sequence of spread spectrum ROM codes, and (iii) a command signal, wherein (i) said clock signal is spread spectrum modulated and (ii) said spread spectrum modulation of said clock signal is switched on in response to a first state of said command signal and switched off in response to a second state of said command signal;
- and
- a second circuit configured to synchronize said command signal to a feedback signal, wherein said sequence of spread spectrum ROM codes is generated according to a predetermined mathematical formula and optimized in accordance with predetermined criteria.
A spread spectrum clock generator circuit comprising:
- means for generating a clock signal in response to (i) a reference signal, (ii) a sequence of spread spectrum ROM codes and (iii) a command signal, wherein (i) said clock signal is spread spectrum modulated and (ii) said spread spectrum modulation of said clock signal is switched on in response to a first state of said command signal and switched off in response to a second state of said command signal;
- and
- means for synchronizing said command signal to a feedback signal, wherein said sequence of spread spectrum ROM codes is generated according to a predetermined mathematical formula and optimized in accordance with predetermined criteria.
A method for controlling a spread spectrum transition comprising the steps of:
- generating a clock signal in response to (i) a reference signal, (ii) a sequence of spread spectrum ROM codes and (iii) a command signal, wherein (i) said clock signal is spread spectrum modulated and (ii) said spread spectrum modulation of said clock signal is switched on in response to a first state of said command signal and switched off in response to a second state of said command signal;
- and
- synchronizing said command signal to a feedback signal, wherein said sequence of spread spectrum ROM codes is generated according to a predetermined mathematical formula and optimized in accordance with predetermined criteria.
An apparatus comprising:
- a first circuit configured to generate a clock signal in response to (i) a reference signal, (ii) a sequence of spread spectrum ROM codes, (iii) a command signal and (iv) a feedback signal;
- and
- a second circuit configured to synchronize said command signal to said feedback signal, wherein said sequence of spread spectrum ROM codes is generated according to a predetermined mathematical formula a nd optimized using a computer program to simulate a transient behavior of said apparatus.
Dependencies are inferred from the claim text.