摘要
在对频率输出的传感器测量中,经常碰到的一个问题是如何高精度测量由测量参数引起的小频率增量问题。许多研究使用D触发器得到待测的可变频率和参考的固定频率的差频。通过理论分析,对D触发器用于差频时的输出特性进行了研究。结果表明:即使两输入信号的频率固定,D触发器差频输出的周期不唯一。如果一个时钟信号周期的误差不影响到测量精度,D触发器可作为两信号的差频器件。实际应用时,参考信号的频率应大于待测信号频率的最大值,并将其接在"CLK"端。
In the design of measuring circuits based on frequency transducers, it is frequently necessary to measure small frequency increments, which is caused by the change of the measured parameter. D flip -flop mixer, which receives two signal input of different frequencies and develops an output signal whose frequency is equal to the frequency difference between the input signals, was widely used in much research and development activity. The output characteristics of a D flip - flop mixer were studied in theory. The output period of the D flip - flop mixer was variable though two input frequencies were invariable. A D′ flip- flop can be used as a mixer and produces an output which is the difference of the two input frequencies when ＋/ - Tck has no unacceptable influence on measuring accuracy. The reference oscillator frequency should be greater than the maximum monitor frequency and should be fed to the clock input of the flip - flop in a practical circuit.
出处
《机械研究与应用》
2009年第5期126-127,130,共3页
Mechanical Research & Application
关键词
D触发器
混频器
差频
输出特性
D flip - flop
mixer
frequency difference
output performance
