Autotracking switch type charge pump for phase lock loop

Abstract

The invention discloses an autotracking switch type charge pump for a phase lock loop, comprising a pull-up circuit, a pull-down circuit and a feedback control circuit, wherein the pull-up circuit comprise a pull-up switch transistor and a pull-up current mirror; the pull-down circuit comprises a pull-down switch transistor and a pull-down current mirror; the feedback control circuit comprises a PMOS (P-channel Metal Oxide Semiconductor) transistor and a NMOS (N-channel Metal Oxide Semiconductor) transistor and is used for controlling the magnitude of the charging / discharging current dynamically; and the switch transistors are connected to the source end, the drain end and the grid end of the current mirror and respectively correspond to three type of charge pumps of an autotracking source switch type, an autotracking drain switch type and an autotracking grid switch type. The autotracking switch type charge pump provided in the invention realizes non-constant current and ensures the charging current to be in dynamic tracking matching with the discharging current. Compared with the structure of the traditional charge pump, the charge pump in the invention has no need of a feedbackamplifier and an external bias current, uses the least number of transistors, has simple structure, and is easy to realize.

Description

technical field [0001] The invention relates to the technical field of analog integrated circuit design, in particular to a self-tracking switching charge pump used in a phase-locked loop, which can be applied to a charge pump phase-locked loop (Charge Pump Phase-Locking Loop CPPLL). Background technique [0002] The phase-locked loop (PLL) circuit was first proposed by H. de Bellescize in 1932, because of its excellent diversity, it has been widely used in the fields of electronics and communication. As an important application example, a phase-locked loop can be used to generate an output signal whose frequency is programmable, equal to a rational fractional multiple of a fixed input frequency. This kind of frequency synthesizer based on phase-locked loop is widely used in wireless terminal products. The diversity of the phase-locked loop also makes it applied to the digital system for the recovery of the clock signal and the generation of the clock signal. [0003] fig...

AI Technical Summary

Problems solved by technology

(2) The structure is complex, and the traditional charge pump structure needs to provide bias current and feedback amplifier to meet the performance requirements

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