A reusable phase-locked loop low-pass filter

Abstract

The invention discloses a reusable phase-locked loop low-pass filter, comprising a channel 1 circuit, a channel 2 circuit and a switching circuit that are in circuit connection; the channel 1 circuit is connected with an outer channel 1 charge pump; and the channel 2 circuit is connected with a channel 2 charge pump. By the reusable phase-locked loop low-pass filter of the invention, the chip space can be saved, thereby solving the problem that the area of the low-pass filter is bigger, not easy for an integration; the cost is saved, and the stability of the loop can be guaranteed.

Description

technical field [0001] The invention relates to a low-pass filter, in particular to a reusable phase-locked loop low-pass filter. Background technique [0002] In the prior art, the frequency synthesizer is often used to provide an accurate reference frequency for the integrated circuit, and the low-pass filter in the frequency synthesizer is used to filter out the high-frequency component of the output voltage of the phase detector, and take a stable average value to control the oscillation the frequency of the device. Generally, in order to obtain better noise suppression, the loop bandwidth of the frequency synthesizer is selected to be relatively small, which leads to relatively large capacitance and resistance of the low-pass filter. If such a large capacitor and resistor are integrated in the chip, it will occupy a huge chip area and greatly increase the cost of the chip. Moreover, due to the process deviation in the production process, the capacitance value and resi...

AI Technical Summary

Problems solved by technology

The disadvantages of this are that the number of off-chip components increases, the complexity of the system increases, and the cost increases

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