Configurable locking detection circuit applicable to charge pump phase-locked loop

Abstract

The invention provides a configurable locking detection circuit applicable to a charge pump phase-locked loop. The configurable locking detection circuit comprises a clock phase difference comparisoncircuit, a locking counter B203, an unlocking counter B204 and an SR latch SR251; the clock phase difference comparison circuit receives two clock signals input from outside and performs phase difference comparison; when the phase difference absolute value is less than or equal to the time window length, the locking counter B203 is enabled; the unlocking counter B204 is reset and forbidden; otherwise, the unlocking counter B204 is enabled; the locking counter B203 is reset and forbidden; the output ends of the locking counter B203 and the unlocking counter B204 are connected to the R end and the S end of the SR latch SR251; and the output end of the SR latch SR251 is the locking indication signal of the configurable locking detection circuit. By means of the circuit provided by the invention, the false unlocking probability can be reduced; and the reliability of the locking detection circuit is improved.

Description

technical field [0001] The invention relates to a configurable locking detection circuit suitable for a phase-locked loop of a charge pump, belonging to the technical field of integrated circuits. Background technique [0002] Phase-locked loop is a frequency and phase synchronization technology realized by feedback control principle, which can provide low-noise clock signal, and has been widely used in wireless communication, navigation, computer and other fields. The charge pump phase-locked loop is a typical representative of the digital-analog hybrid phase-locked loop. Its theoretical static phase error is zero, and it has significant advantages such as high speed, low jitter, and low power consumption. It is currently the most widely used phase-locked loop. The basic structure of the charge pump phase-locked loop is as follows: figure 1 shown. [0003] The lock detection circuit is an important module in the phase-locked loop of the charge pump, which is used to detec...

AI Technical Summary

Problems solved by technology

At present, the charge pump phase-locked loop is mostly used as a wide frequency frequency synthesizer, and may need to work in a complex environment

In this case, the traditional non-configurable lock detection circuit may fail, affecting the normal operation of the integrated circuit system

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