Phase-locked loop circuit and communication chip

Abstract

A phase-locked loop circuit and a communication chip belong to the field of integrated circuits, and a modulation circuit outputs a first feedback current and a second feedback current according to a modulation voltage and a frequency division control signal; a phase frequency detector detects a phase difference between an input clock signal and a first clock signal and generates a first control signal; a charge pump performs charging and discharging according to the first control signal and the second feedback current so as to output a first control voltage; a main loop filter adjusts an adjustable resistor in the main loop filter according to the first feedback current so as to modulate the first control voltage and generate a modulation voltage; a voltage-controlled oscillator outputs an output clock signal of which the frequency is in direct proportion to the modulation voltage; a feedback frequency divider performs frequency division of a preset frequency division ratio on the output clock signal according to the frequency division control signal so as to output a first clock signal; the square root of the preset frequency dividing ratio divided by the quotient of the second feedback current is a first coefficient, and the ratio of the resistance value of the adjustable resistor to the first coefficient is a constant; the loop stability of the phase-locked loop is improved.

Description

technical field [0001] The application belongs to the field of integrated circuits, and in particular relates to a phase-locked loop circuit and a communication chip. Background technique [0002] Due to the advantages of flexible frequency adjustment and frequency synthesis, phase-locked loops have become an indispensable part of modern integrated circuits. Although the structure of the phase-locked loop circuit is basically the same, due to different applications, the requirements for the performance parameters of the phase-locked loop are also different, such as input and output frequency range, frequency division range, output signal jitter, phase noise, power consumption and area, etc. . Different clock generation circuits need to be specially designed for each application. If a phase-locked loop can cover the application range of multiple systems, it is not necessary to design different clock generation circuits for each system, which can greatly reduce design time a...

AI Technical Summary

Problems solved by technology

[0005] The purpose of this application is to provide a phase-locked loop circuit and a communication chip, aiming to solve the problems of the traditional phase-locked loop circuit when outputting at a wide frequency, the loop stability is poor, the damping factor changes with the input reference frequency and is affected by the process and voltage. and the problem of the influence of temperature conditions

Images