| 摘要 |
PCT No. PCT/SE95/00813 Sec. 371 Date Jun. 3, 1997 Sec. 102(e) Date Jun. 3, 1997 PCT Filed Jun. 30, 1995 PCT Pub. No. WO96/01007 PCT Pub. Date Jan. 11, 1996The phase difference of two periodic input signals having essentially the same frequency are measured in, for example, a communication system, in an accurate way with a high resolution and utilizing digital components. A high resolution digital phase detector which can be included in a phase locked loop comprises an oscillator providing a clock signal having a high frequency that is not an integer multiple of the frequency of the input signals. The clock signal is provided to a clock signal input of a counter, and the periodic signals are fed to the start and stop terminals of the counter. Output terminals of the counter are directly connected to inputs of a digital low-pass filter in which an average value calculation is carried out of the integer values of the output of the counter. Because of the small frequency deviation from the integer multiple value, a slow sliding of the oscillator phase compared to the phase of the input signals is achieved, such that all possible integer values on the output of the counter are run through. A very accurate calculation of the phase position is achieved by the average value calculation of these integer values in the low-pass filter. In a complete phase-locked loop, a voltage controlled oscillator provides one of the input signals to the counter through a divider circuit.
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