Low-noise source end switching charge pump for phase-locked loop

Abstract

The invention discloses a low-noise source end switching charge pump for a phase-locked loop. The low-noise source end switching charge pump comprises a first PMOS tube, a second PMOS tube, a first current source, a third PMOS tube, a fourth PMOS tube, a fifth PMOS tube, a sixth PMOS tube, a first NMOS tube, a second NMOS tube, a second current source, a third NMOS tube, a fourth NMOS tube and a fifth NMOS tube, wherein the gate terminal of the fifth PMOS tube receives a first pulse signal, the source terminal and the drain terminal have short circuit and are connected to the drain terminal ofthe third PMOS tube; the gate terminal of the sixth PMOS tube receives the first pulse signal, the source terminal receives 1 / 2 supply voltage, and the drain terminal is connected to the drain terminal of the third PMOS tube; the gate terminal of the fifth NMOS tube receives reversed pulse of a second pulse signal, the source terminal and the drain terminal have short circuit and are connected tothe drain terminal of the third NMOS tube. The low-noise source end switching charge pump for the phase-locked loop can be applicable to low-voltage applications, and the noise generated by charge sharing of a switch tube can be cancelled.

Description

technical field [0001] The invention relates to the technical field of phase-locked loops, in particular to a phase-locked loop low-noise source switch charge pump. Background technique [0002] A phase-locked loop (PLL, Phase Lock Loop) can generate a clock that is consistent with an input reference clock in frequency and phase, and is widely used in synchronous applications. Charge-pump phase-locked loop (CPLL) is widely used due to its advantages of high speed, low power consumption, wide frequency capture range and low cost. [0003] figure 1 It is a circuit schematic diagram of a common charge pump phase-locked loop in the prior art, such as figure 1 As shown, the charge-pump phase-locked loop consists of five parts: phase frequency detector (PFD), charge pump (CP), loop filter (LPF), voltage-controlled oscillator (VCO) and frequency divider (Divider). constitute. Among them, the charge pump (CP) converts the error pulse (UP, DN) output by the phase frequency detect...

AI Technical Summary

Problems solved by technology

[0016] The source side switches the charge pump, the switching noise will not directly affect the output side, and the size of the switch tube can be increased in low-voltage applications, but the charge sharing caused by the switch tube will still generate noise and reduce the performance of the phase-locked loop (PLL).

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