Silicon Laboratories Inc.
Ring oscillator based RC calibration circuit

Abstract:

A calibration operation adjusts a frequency of a ring oscillator to a desired frequency by adjusting programmable RC circuits in the stages of the ring oscillator. The programmable RC circuits have programmable capacitors, resistors, or both. The RC circuits account for most of the delay through the ring oscillator. Another circuit with its own RC time constant is calibrated based on the adjustments made to the RC circuits in the ring oscillator to achieve the desired frequency.