Charge pump circuit

Abstract

The invention provides a charge pump circuit. The charge pump circuit comprises a group of differential complementary metal-oxide-semiconductor (MOS) switch circuits, a reference voltage negative feedback circuit, a group of N-channel metal-oxide-semiconductor (NMOS) current mirrors and a group of P-channel metal-oxide-semiconductor (PMOS) current mirrors, wherein the group of NMOS current mirrors and the group of PMOS current mirrors are respectively connected to the differential complementary MOS switch circuits and the reference voltage negative feedback circuit for providing mirror currents; and the reference voltage negative feedback circuit is connected with differential complementary MOS switches, so that the reference voltage negative feedback circuit provides feedback for the differential complementary MOS switches. Currents flowing through two groups of complementary differential MOS switches are completely matched through the feedback action of the reference voltage negative feedback circuit on the differential complementary MOS switches, so that the ripple voltage generated at an output voltage end due to unmatched current sources is effectively reduced, and the output noise performance of a phase locked loop is greatly improved.

Description

technical field [0001] The invention relates to a charge pump circuit, in particular to a charge pump circuit arranged in a phase-locked loop circuit. Background technique [0002] figure 1 It is a structural schematic diagram of a charge pump circuit commonly used in a phase-locked loop circuit in the prior art. Such as figure 1 As shown, M5 / M6 / M15 / M16 in the figure are MOS switches, Up / Upb, Dn / Dnb come from two pairs of differential signals output by the frequency and phase detector. Reference numeral A1 denotes a unity gain amplifier, which functions to cancel charge sharing. In the phase-locked loop circuit design, the output voltage Vout of the charge pump is a very critical design factor. [0003] exist figure 1 In the traditional charge pump shown, if the currents generated by the NMOS and PMOS current mirrors do not match, ripples will be caused on the output voltage terminal Vout, thereby increasing the output jitter of the phase-locked loop circuit. Contents...

AI Technical Summary

Problems solved by technology

[0004] In order to overcome the current mismatch between the charge pump circuit NMOS and the PMOS current mirror that exists in the above-mentioned prior art, causing ripples on the output voltage, thereby increasing the output jitter problem of the phase-locked loop circuit, the main purpose of the present invention is to provide a The charge pump circuit used in the phase-locked loop circuit, through the feedback effect of the reference voltage negative feedback circuit on the differential complementary MOS switch, makes the currents flowing through the complementary two sets of differential MOS switches fully match, effectively reducing the current caused by the current source. The ripple voltage caused by the mismatch at the output voltage terminal greatly improves the output noise performance of the PLL circuit

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