Rapidly locked charge pump phase-locked loop

Abstract

The invention discloses a phase-locked loop of a fast-locked charge pump, which includes a phase-locked loop composed of a frequency and phase detector, a charge pump, a low-pass filter, a voltage-controlled oscillator and a frequency divider, wherein the voltage-controlled The oscillator includes a voltage conversion current module and a current-controlled oscillator module; an initialization circuit that generates an initial oscillation frequency is added to the voltage-controlled oscillator in the phase-locked loop; the initialization circuit includes a symmetrical transconductance operational amplifier and a A transistor circuit connected to the switch of the low pass filter, and a transmission gate TG and an inverter INV connected across the low pass filter. The present invention adds an additional initialization circuit to the voltage-controlled oscillator, which can speed up the locking speed of the phase-locked loop, thereby reducing the locking time of the phase-locked loop. At the same time, the initialization circuit has a simple structure, fewer transistors, and does not significantly increase the overall charge Layout area of ​​the pump phase-locked loop.

Description

technical field [0001] The invention relates to a charge-pump phase-locked loop in the field of integrated circuits, in particular to a charge-pump phase-locked loop capable of fast loop locking without significantly increasing the layout area of ​​the phase-locked loop. Background technique [0002] A phase-locked loop is a negative feedback system that can synchronize the frequency and phase of the input signal and the output signal. It can be classified into: analog phase-locked loop, digital-analog hybrid phase-locked loop, all-digital phase-locked loop and software phase-locked loop. The charge pump phase-locked loop is a kind of digital-analog hybrid phase-locked loop. Because of its simple structure, good performance, and the advantages of zero theoretical input phase error, it is widely used in communication, computer, space technology and other fields. [0003] The loop lock time is an important performance parameter of the charge pump phase-locked loop. Commonly u...

AI Technical Summary

Problems solved by technology

Dynamically changing the loop bandwidth requires an additional phase difference detection circuit, and the phase difference detection circuit is more complicated

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