ADPLL circuit with adjustable phase

Abstract

The invention discloses a phase-adjustable ADPLL circuit, which belongs to the field of digital circuits and comprises a phase discriminator, a lock loss detection module, a phase-adjustable module, a digital filter, a DCO, an AFC module and a frequency divider. Wherein the phase discriminator, the lock loss detection module, the phase adjustable module, the digital filter and the DCO are connected in sequence, the lock loss detection module, the AFC and the DCO form a loop, and the DCO, the frequency divider and the phase discriminator form a loop. The lock losing detection module and the phase adjustable module are added behind the phase discriminator, the lock losing detection module is used for generating the locking signal Lock, and the phase adjustable module is used for generating the adjusted phase difference signal PDadj, so that phase adjustability in an ADPLL internal loop and monitoring on whether the loop is locked are realized, and the accuracy of phase adjustment in the ADPLL internal loop is improved. And the circuit is simple in structure, easy to implement and high in reusability.

Description

technical field [0001] The invention relates to the technical field of digital circuits, in particular to an ADPLL circuit with adjustable phase. Background technique [0002] Phase-Locked Loop (PLL) is a circuit with a feedback mechanism. In a PLL, the output of the oscillator is compared with a reference signal, and based on the difference, the oscillator is calibrated. Ideally, when the PLL is locked, the oscillator output frequency is the same as the expected oscillation frequency, and the phase error with the reference signal is maintained within a set range. With the development of digital circuit technology, the phase-locked loop is developing in the direction of digitization, generalization and integration. ADPLL (All-Digital Phase-Locked Loop, all-digital phase-locked loop) has developed into a new research object. The all-digital phase-locked loop uses digital circuits to realize the functions of the analog circuit. Compared with the analog phase-locked loop, the...

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Problems solved by technology

This circuit can handle the short-term loss of lock caused by phase mutation, but the circuit structure is complicated and many components are used; the patent CN202111084728.3 provides a digitally controlled oscillator, which can realize dynamic phase selection, but the phase adjustment module needs to be designed together with the DCO , which increases the difficulty of DCO design, and the circuit structure is complex and the reusability is not high

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