A frequency divider circuit and frequency synthesizer

Abstract

The invention relates to the field of circuit design, and discloses a frequency divider circuit and a frequency synthesizer. When the input terminals of the output unit are all at low level, the frequency divider circuit starts to work, and before the first rising edge of the initial clock signal arrives, the output The output of the unit is a high-level frequency division clock signal; after the first rising edge of the initial clock signal comes, the binary number corresponding to the M input terminals of the output unit is equal to the frequency division ratio input N. Due to the function of the counting unit, the initial clock Every time the rising edge of the signal comes, the binary number corresponding to the M input terminals of the output unit will be reduced by one. During this period, the frequency division clock signal is always low until the Nth rising edge of the initial clock signal comes. The frequency-divided clock signal becomes high again and enters the next period. It can be seen that the period of the frequency-divided clock signal is N+1 times that of the initial clock signal, which realizes the purpose of dividing the frequency of the initial clock signal, and the design process is simple.

Description

technical field [0001] The invention relates to the field of circuit design, in particular to a frequency divider circuit and a frequency synthesizer. Background technique [0002] In the field of integrated circuits, frequency synthesizers are often used to multiply the frequency of the input signal. The frequency multiplication function of the frequency synthesizer needs to be realized by a frequency divider circuit and a feedback loop. The frequency divider circuit divides the output signal of the frequency synthesizer to generate feedback signal, and then compare the feedback signal with the input signal of the frequency synthesizer, and make the frequency of the feedback signal equal to the frequency of the input signal of the frequency synthesizer through the feedback loop, and finally realize the purpose of multiplying the frequency of the input signal by the frequency synthesizer. It can be seen that, The frequency divider circuit is very important. In the prior art,...

AI Technical Summary

Problems solved by technology

[0002] In the field of integrated circuits, a frequency synthesizer is often used to multiply the frequency of the input signal. The frequency multiplication function of the frequency synthesizer needs to be realized through a frequency divider circuit and a feedback loop. The frequency divider circuit divides the output signal of the frequency synthesizer to generate Feedback signal, and then compare the feedback signal with the input signal of the frequency synthesizer, and make the frequency of the feedback signal equal to the frequency of the input signal of the frequency synthesizer through the feedback loop, and finally achieve the purpose of frequency multiplication of the input signal by the frequency synthesizer. It can be seen that The frequency divider circuit is very important. In the prior art, a digital frequency divider composed of pure digital circuits is often used. The design process needs to combine circuit design with coding, and the process is very complicated.

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