Phase-locked loop circuit used for spurious suppression and spurious suppression method thereof

Abstract

The invention discloses a phase-locked loop circuit used for spurious suppression and a spurious suppression method thereof. The phase-locked loop circuit comprises a main loop of a phase-locked loop and a spurious suppression circuit, wherein the main loop of the phase-locked loop comprises a phase frequency detector, a charge pump, a loop filter, a voltage-controlled oscillator and an N frequency divider, wherein the output of the N frequency divider is connected to the input of the phase frequency detector; the spurious suppression circuit comprises a phase measuring circuit and a charge pump mismatching current callback circuit; the input of the phase measuring circuit is connected to the output of the phase frequency detector; the output of the phase measuring circuit is connected to the input of the charge pump mismatching current callback circuit; the input of the charge pump mismatching current callback circuit is also connected to the output of the phase frequency detector; and the output of the charge pump mismatching current callback circuit is connected to the charge pump. According to the phase-locked loop circuit, the phase measuring circuit and the charge pump mismatching current callback circuit are added into the conventional phase-locked loop circuit, and the mismatching current of the charge pump is precisely detected and recharged, so that the spurious output of the phase-locked loop is greatly reduced.

Description

technical field [0001] The invention relates to the technical field of phase-locked loops, in particular to a phase-locked loop circuit for suppressing spurs and a stray suppression method thereof. Background technique [0002] In the electronic system, the phase-locked loop is one of the most commonly used circuits. The phase-locked loop locks the output frequency of the voltage-controlled oscillator VCO at the required frequency point by comparing with the reference signal, which is flexible and convenient for other electronic systems. The module provides the required high-performance clock. With the continuous improvement of the integrated circuit performance, the electronic system has higher and higher requirements for the high-frequency clock generated by the phase-locked loop. [0003] Although the traditional phase-locked loop can generate accurate clock signals, due to the different electrical parameters of the NMOS tube and the PMOS tube, the follow-up ability of th...

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Problems solved by technology

[0003] Although the traditional phase-locked loop can generate accurate clock signals, due to the different electrical parameters of the NMOS tube and the PMOS tube, the follow-up ability of the charge pump amplifier is limited, and other reasons such as power supply ripple and reference clock feedthrough will cause a cycle time The sum of charge and discharge of the charge pump in the segment to the frequency control line of the voltage-controlled oscillator is not zero, resulting in periodic fluctuations in the control voltage of the voltage-controlled oscillator, resulting in phase detection spurious

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