Phase-locked loop circuit with rapid frequency locking function

Abstract

The invention relates to a phase-locked loop circuit with a quick frequency locking function, which comprises a control circuit unit, a phase-locked loop circuit unit, a reset circuit consisting of R1, C3 and SW1, a single chip microcomputer port 7, a clock circuit consisting of capacitors C1 and C2 and a crystal oscillator Y2, a single chip microcomputer port 5 and a single chip microcomputer port 6, the phase-locked loop circuit unit is composed of a peripheral circuit composed of a PLL chip, a loop filter (LPF) and a voltage-controlled oscillator (VCO), the PLL chip selects LMX2571, the single-chip microcomputer carries out write operation configuration on a register of the LMX2571, a 9-pin CPoutExt port of the LMX2571 outputs a voltage signal, and the signal enters the VCO circuit through the LPF to generate frequency F; the frequency F is divided by a frequency F1 which is obtained through frequency division of the LMX2571 reference frequency to obtain data N, and the data and thedata configured for the LMX2571 are written into a register of the LMX2571 through a single-chip microcomputer to realize frequency control. The frequency locking circuit has a rapid frequency locking function, and is high in precision, high in stability and low in phase noise.

Description

technical field [0001] The invention relates to a feedback control circuit of a wireless communication circuit, in particular to a phase-locked loop circuit with a fast frequency locking function. Background technique [0002] As a typical feedback control circuit, Phase Locked Loop (PLL) uses an external input signal to control the frequency and phase of the internal signal of the loop to generate a high-frequency local oscillator signal to realize the transmission of transceiver signals and frequency modulation signals. Demodulation and other aspects are one of the key components of the wireless communication radio frequency transceiver system. The excellent performance of the phase-locked loop is the premise to ensure high-quality communication. Although phase-locked loop technology has been around for many years, it has adopted integer frequency division technology and fractional frequency division technology, but there are problems of slow locking time and low precision...

AI Technical Summary

Problems solved by technology

Although phase-locked loop technology has been around for many years, it has adopted integer frequency division technology and fractional frequency division technology, but there are problems of slow locking time and low precision. This patent uses a fractional frequency division technology to provide a fast frequency locking technology. , can quickly lock the frequency, and has high precision, strong stability and low phase noise

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