Patent ID: 6819117
Filing Date: 2004-11-16
Classification: G01R

Abstract:
A method of calibrating a timer having a coarse measurement capability in which time intervals defined by time-interval boundaries are counted and a fine measurement capability in which time between time-interval boundaries is interpolated using a voltage ramp, comprising:a. Aligning the voltage ramp relative to the time-interval boundaries; b. Determining alignment of the voltage ramp relative to a reference-clock signal having a known relationship to the time-interval boundaries; c. Sampling the voltage ramp at a plurality of known times relative to the time-interval boundaries; and d. Determining slope of the voltage ramp as a function of time from the voltage samples, wherein aligning the voltage ramp comprises starting the voltage ramp at a defined number of periods of the reference-clock signal following coincidence of the interval-clock signal and the reference-clock signal.