Phase difference demodulator.

摘要

Phase difference demodulator (10) for measuring the phase difference between two signals of the same frequency, time multiplexed onto a single analog input (12), and providing a precision digital output signal (32) representing the phase difference. The most significant part of the signal, the upper bits, is determined by digital processes while analog-to-digital processes determines the lower bits. The analog-to-digital processes utilize an integrating capacitor and current sources for demodulating servo bursts for obtaining phase difference. The current sources are a coarse current and a fine current %e in value of the coarse current source. The capacitor is switched in a differential scheme by the integrator to determine error during the digital approximation of the upper bits in analog to digital conversion. The same capacitor and current sources are utilized in the error acquired in analog form and then during the analog-to-digital conversion.