Quick starting circuit for charge pump phase-locked loop

Abstract

The invention belongs to the technical field of an electronic circuit and specifically relates to a quick starting circuit for a charge pump phase-locked loop. The quick starting circuit comprises a phase-frequency detector, a rapid charging module, a charge pump, a low-pass filter, a voltage-controlled oscillator and a frequency divider. The phase-frequency detector is connected with an external clock signal, the input end thereof is connected with the output end of the voltage-controlled oscillator, the first output end thereof is connected with the first input end of the charge pump, and the second output end is connected with the second input end of the charge pump; the output end of the charge pump is connected with the input end of the voltage-controlled oscillator through the low-pass filter; the output end of the rapid charging module is connected with the low-pass filter through a switching tube; the output end of the voltage-controlled oscillator is connected with the input end of the frequency divider; the output end of the frequency divider outputs an enable signal through a D trigger; and the enable signal is connected to the control end of the switching tube. The circuit has the beneficial effect of providing the charge pump phase-locked loop capable of rapidly locking.

Description

technical field [0001] The invention belongs to the technical field of electronic circuits, and in particular relates to a quick start circuit for a phase-locked loop of a charge pump. Background technique [0002] In the field of electronics and communication, the phase-locked loop has become an indispensable basic device. With the development and maturity of large-scale integrated circuit technology, the phase-locked loop using the charge pump structure is easy to integrate, low power consumption, and low jitter. , No phase difference locking and other advantages have been widely used. Such as figure 1 As shown, the basic charge-pump phase-locked loop includes a phase-frequency detector PFD, a charge pump CP, a low-pass filter LPF, a voltage-controlled oscillator VCO, and a frequency divider DIV. The frequency and phase detector compares the phase and frequency difference of the two signals, and generates a control signal to the charge pump, and the charge pump charges a...

AI Technical Summary

Problems solved by technology

[0004] What the present invention aims to solve is to propose a quick start circuit for a charge pump phase locked loop aiming at the problem that the existing phase locked loop cannot be quickly locked.

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