A Matched Charge Pump Circuit for Phase Locked Loop

Abstract

The invention discloses a matching type charge pump circuit for a phase-locked loop. The matching type charge pump circuit comprises an in-proportion bias circuit, a current duplication circuit, a sunk constant-current source circuit, a pull-up constant-current circuit and a switch circuit. The in-proportion bias circuit magnifies an external reference current proportionally. The current duplication circuit strictly duplicates a current in an NMOS current mirror for a PMOS current mirror. The sunk constant-current source is used for discharging a later-stage load. The pull-up constant-current circuit is used for charging the later-stage load. The switch circuit is used for controlling switching-on and switching-off of a charge-discharge current source. According to the matching type charge pump circuit for the phase-locked loop, the bias current mirror image proportion of the in-proportion bias circuit depends on the ratio of resistance values of a resistor R0 and a resistor R1. The matching type charge pump circuit for the phase-locked loop is more reliable in structure compared with a traditional structure and is not affected by technology angles and temperature variation so as to accurately control loop parameters of the phase-locked loop of a charge pump, and the charge sharing effect existing in common charge pump design is well eliminated.

Description

technical field [0001] The invention relates to a charge pump phase-locked loop (CPPLL), in particular to a matching charge pump circuit for the phase-locked loop, which realizes high matching of the circuit and can significantly reduce the phase noise of the phase-locked loop system. Background technique [0002] CMOS charge pump phase-locked loop circuit (ChargePumpPhase-lockedLoop, CPPLL) has the advantages of high speed, low power consumption, low jitter, low cost and easy integration, etc., and is widely used in frequency synthesis, clock recovery and other circuits. As a key module in the phase-locked loop of the charge pump, the current matching characteristic of the charge pump circuit is directly related to the near-end phase noise performance of the CPPLL. How to further improve the current matching characteristics of the charge pump has always been the focus of charge pump design and research. [0003] An ideal charge pump structure such as figure 1 As shown, it...

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Problems solved by technology

[0004] However, the actual structure of the common charge pump circuit has various non-ideal effects such as clock feedthrough and charge sharing. It is difficult to achieve a perfect match between the pull-up current and sink current of the charge pump under ideal conditions, and the circuit matching characteristics are far from reaching ideal match

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