Patent Number: 7,786,814

Title: Method and apparatus for deriving an integrated circuit (IC) clock with a frequency offset from an IC system clock

Abstract: Generally, methods and apparatus are provided for deriving an integrated circuit (IC) clock signal with a frequency that is offset from the IC system clock. An offset clock having a frequency that is offset from a system clock is generated by configuring a ring oscillator in a first mode to generate the system clock having a desired frequency; and adjusting the configuration of the ring oscillator in a second mode to generate the offset clock having the frequency that is offset from the system clock. The configuration of the ring oscillator is adjusted in the second mode by adjusting (i) a power supply value applied to the ring oscillator in the second mode relative to a power supply value applied in the first mode; or (ii) a number of delay line elements that are active in the ring oscillator loop.

Inventors: Buonpane; Michael S. (Easton, PA), Chlipala; James D. (Emmaus, PA), Martin; Richard P. (Macungie, PA), Segan; Scott A. (Allentown, PA), Wang; Zhongke (Bridgewater, NJ)

Assignee: Agere Systems Inc.

International Classification: H03B 5/24 (20060101)

Expiration Date: 8/31/12018