Digital FNPLL (Fractional-N Phase-Locked Loop) control method and PLL (Phase-Locked Loop)

Abstract

The embodiment of the invention provides a digital FNPLL (Fractional-N Phase-Locked Loop) control method and a PLL (Phase-Locked Loop). The PLL comprises a control device, a TDC (Time-to-Digital Converter), a DLF (Digital Loop Filter), a DCO (Digital Controlled Oscillator), a DIV (Frequency Divider) and an SDM (Sigma-Delta Modulator), wherein the control device is used for carrying out delay processing on an effective edge of a reference clock according to a frequency control word and a fractional frequency control word to obtain a delayed reference clock; the delayed reference clock is sent to the TDC for enabling the TDC to carry out phase detection processing on the delayed reference clock and a feedback clock. According to the PLL provided by the invention, the control device which is additionally arranged in the PLL can be used for carrying out the delay processing on the reference clock according to the current frequency control word and the fractional frequency control word, so that the feedback clock and the delayed reference clock are enabled to have similar effective edge corresponding time, the TDC just needs to process phase detection signals in a very small time-domain input range, the design difficulty of the TDC and the needs on the resolution rate of the TDC are greatly reduced, the design of the TDC can be simple and free, and the design DOF (Degree Of Freedom), the simplicity and the effectiveness of the PLL are ensured.

Description

technical field [0001] The invention belongs to the field of electronic technology, and in particular relates to a digital fractional frequency division phase-locked loop control method and the phase-locked loop. Background technique [0002] In radio frequency transceivers, a frequency synthesizer based on a Phase-Locked Loop (PLL) structure is widely used to generate a local oscillator signal, referred to as a local oscillator signal, to complete a frequency shift operation of a data signal. [0003] In a wireless communication system, especially in a wireless terminal, due to factors such as cost, a Zero Intermediate-Frequency (ZIF) radio frequency transceiver architecture is widely used. In a radio frequency transceiver of this type of architecture, no matter it is a signal transmitting channel or a signal receiving channel, it is required that the frequency of the local oscillator signal is exactly the same as that of the radio frequency carrier frequency signal. That ...

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Problems solved by technology

However, there is usually a relatively close compromise between range and accuracy, and it is often difficult to meet the requirements of the above two dimensions

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