Phase-locked loop circuit, system with multiple phase-locked loops and output phase synchronization method thereof

Abstract

The invention provides a phase-locked loop circuit, a system with multiple phase-locked loops and an output phase synchronization method thereof. The invention includes a frequency divider for frequency division of an output signal, a sampler which samples the frequency-divided signal based on the output signal to obtain a feedback signal to ensure that the phase of the feedback signal is consistent with the phase of the output signal, a phase frequency detector which determines the phase difference between the feedback signal output by the sampler and the input crystal oscillator signal to generate a pulse signal, a charge pump which generates tuning voltages based on the pulse signal, and a voltage controlled oscillator which adjusts the frequency of the output signal based on the tuningvoltages. In the invention, a sampling method is adopted to realize the phase consistency of the feedback signal and the output signal of the phase-locked loop circuits. Thus the phase consistency between the output signal and the input crystal oscillator signal is greatly improved. Besides, in the system with multiple phase-locked loops, the phase of the output signals of all phase-locked loop circuits is ensured to be consistent so as to improve the system performance.

Description

technical field [0001] The invention relates to the technical field of wireless communication integrated circuits, in particular to a phase-locked loop circuit, a multi-phase-locked loop system and an output phase synchronization method thereof. Background technique [0002] Phase locked loop (phase locked loop, PLL), as the name implies, is a phase-locked loop, which is a typical feedback control circuit. It uses an external input reference signal to control the frequency and phase of the internal oscillation signal of the loop, and realizes the output signal frequency. Automatic tracking of input signal frequency, generally used in closed-loop tracking circuits. The phase-locked loop is a method to stabilize the frequency in radio transmission. In order to keep the frequency unchanged, it is required that the phase difference between the crystal oscillator and the phase-locked loop output signal does not change. If there is a change in the phase difference, it is related t...

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Problems solved by technology

However, using the traditional Type-II phase-locked loop structure, the frequency divider output of a single phase-locked loop can be aligned with the reference clock phase. There are different degrees of delay errors in the phases of the phase-locked loop frequency divider output signal and the voltage-controlled oscillator output signal. As a result, even if the crystal oscillator signals input to all transceiver phase-locked loops have the same phase, due to the delay of the frequency divider The relationship between time and time is different, and finally the local oscillator signal provided by each transceiver cannot maintain the same phase

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