A fast response charge pump circuit for a phase-locked loop

Abstract

The invention claims a fast response charge pump circuit for a phase-locked loop, comprising a self-biasing cascode bias circuit, a DN differential fractional-mode conversion circuit, a replica circuit, a charge-discharge circuit and a UP differential fractional-mode conversion circuit, wherein the charge-discharge circuit comprises a self-biasing cascode bias circuit, a DN differential fractional-mode conversion circuit and a UP differential fractional-mode conversion circuit. A self-biasing cascode bias circuit is used to provide current bias for the core circuit of the charge pump. The channel length modulation effect of a single MOS transistor is effectively overcome, and the matching accuracy of the charge current and the discharge current of the charge pump is improved. Compared withthe traditional cascode bias circuit, the output voltage swing of the charge pump circuit is improved, and the power supply voltage is reduced. The charge / discharge current is supplied by the upper and lower current sources, which restrains the change of charge / discharge current with the output voltage and improves the matching range of charge / discharge current of the charge pump. Using the sameswitch tube as the charge pump switch, the inherent mismatch between different switch tubes can be avoided effectively. Positive feedback mechanism is adopted to improve the response speed of the switch.

Description

technical field [0001] The invention belongs to the field of integrated circuit design, and in particular relates to a fast-response charge pump circuit for a phase-locked loop. Background technique [0002] The charge pump phase-locked loop has the advantages of wide capture range, short capture time, large linear range, high speed and low power consumption, and has been widely used in modern communication and radio frequency fields. The charge pump phase-locked loop is mainly composed of five parts: phase frequency detector (PFD), charge pump (CP), loop filter (LPF), voltage controlled oscillator (VCO) and frequency divider (Divider). Among them, the charge pump circuit is the main circuit module in the charge pump phase-locked loop. Its main function is to convert the digital control signal (including charging signal and discharging signal) output by the phase frequency detector (PFD) into an analog signal, and then control The output frequency of the voltage-controlled ...

AI Technical Summary

Problems solved by technology

[0004] However, traditional charge pumps have problems such as low matching accuracy of charging / discharging current and small matching range of charging / discharging current, which directly affect the loop performance of the phase-locked loop.

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