Asynchronous sample rate tracker

摘要

An asynchronous sample rate tracker based on a phase-locked loop quickly locks to an input sample rate, even when the input sample rate equals the resident, or internal, sample rate of an asynchronous digital sample rate converter. The phase difference between the input write data and output read data is maximized to reduce data lost due to excursions in the input sample rate. In one embodiment, a binary shift register is used to generate a read pointer step size according to the derivative of the difference between a write pointer position and a read pointer position.