A Method of High Resolution Digital Linear Phase Comparison

SummaryHigh resolution measurement of frequency and frequency stability is crucial to the development of many modern technologies such as frequency sources, timing and punctuality. According to the law of phase difference change between periodic signals, a digital linear phase comparison method is presented. By using digital technology, measurement dead zone can be avoided. The phase value of sine signal linear area is selected by controlling the phase discrimination area to estimate the frequency stability, which improves the resolution and accuracy of sampling phase information of analog-to-digital converter. The sampling efficiency is improved by using the method of frequency doubling or frequency dividing of the reference signal. By controlling the sampling time interval with the method of counting the reference clock, the frequency stability of the measured signal can be measured from transient to long-term, realizing the frequency stability measurement in the whole frequency domain. In the digital linear phase comparison system, a 14-bit high-speed analogue-to-digital converter is used as the phase detection device. Experiment results show that the background noise of the system of the prototype at the nominal frequency of 10MHz is 2.12×10−5/100ns,1.93×10−12/s,2.41×10−16/10000s.