A new high-precision frequency and duty cycle measurement method with FPGA implementation

A new method of high precision frequency measurement is proposed based on the non-AD sampling and non-analog circuit. First, the input signal is shaped by the digital system´s comparison of hysteresis, then the shaped signal is measured by the equal precision frequency measurement method, through which the none synchronized phase problem is eliminated successfully. Second, the proposed method is no longer directly dependent on the rising and falling edges of input signal. So the proposed method has wider frequency range, and it also has the ability to directly measure the periodic signals which meet the requirements of offset and peak like sine wave, triangle wave and so on. In addition, it can tolerate the input signal which has a certain degree of disturbance and edge jitter. The result shows that the proposed method has advantages of low cost, high speed, high precision, etc. this method can be widely used in future, and it has been designed and verified on the FPGA in this paper.