Cypress Semiconductor Corporation

Integrated Circuit Systems, Inc.

Gregory Richmond

Arda Kamil Bafra

Ignatius S Bezzam

Aysel Yildiz

Herbe Q Chun

A method and circuit for performing switching in a frequency timing generator is described. The method includes detecting a request for a new value for a feedback counter or an reference counter, upon which a loading operation is synchronized for the appropriate counter. A time-out order of the feedback counter and the reference counter is determined. Where no time-out order difference is detected therein, a state machine status word function is completed. Where a time-out order difference is detected therein, it is determined which of the reference counter and the feedback counter times out first. Where the reference counter times out first, a constant charge pump current is delivered to a loop filter associated with a phase locked loop to achieve an upward frequency direction. Where the feedback counter times out first, a constant charge pump current is delivered to the loop filter to achieve a downward frequency direction.

Analog based, state machine controlled, frequency smooth switching method for frequency timing generators

A radio frequency synthesizer receives a relatively low frequency input signal and synthesizes from it a high frequency output signal whose frequency can be programmed to change in fine steps, for use e.g. in cordless telephone. The frequency synthesizer includes three linked phase locked loops with a single side band mixer in one embodiment coupling two of the phase locked loops together. This provides an output signal free of in-band frequency spurs within the spacing of two channels. The synthesizer can be integrated in a single chip with a narrowband FM modulation circuit. In spite of using a novel synthesizer to achieve monolithic integration, the user programming interface and control value equations are the industry standard format.

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Sunnyvale, CA, United States of America

Gregory Richmond