Switching Frequency Detector and Phase-Locked Loop Based on Periodic Comparison

Abstract

The invention relates to a switching type phase frequency detector based on periodic comparison and a digital phase-locked loop with the phase frequency detector. The phase frequency detector comprises a frequency division module and a phase frequency detection module. The frequency division module is used for performing divide-by-two frequency division on a feedback signal to generate divide-by-two frequency division signals (divby2 signals); and the phase frequency detection module is used for sampling the divby2 signals at rising edges and falling edges of a reference signal respectively, and for performing frequency comparison on the sampled data from the falling edges and performing phase comparison on the sampled data from the rising edges to generate phase differences and frequency differences. The digital phase-locked loop comprises the phase frequency detector, a digital filter, a digital-controlled oscillator and a frequency divider. With the phase frequency detector, auxiliary circuits are not required for discriminating differences of phases and frequencies, so that complexity and power consumption of loops are reduced, and locked time of the loops is shortened; and the entire circuit is realized digitally, and has excellent transportability, so that noise performance of the loops is improved.

Description

technical field [0001] The invention belongs to the field of radio frequency integrated circuits, and in particular relates to a switch-type frequency and phase detector based on cycle comparison, and a digital phase-locked loop using the frequency and phase detector. Background technique [0002] With the development of integrated circuit (Integrated Circuit, IC) process technology, the cost and power consumption of digital circuits are gradually reduced; at the same time, digital circuits can also be easily converted between different processes, so more and more circuits are Digitizing. The phase locked loop (phase locked loop, PLL) as an important circuit of radio frequency (Radio Frequency, RF) integrated circuit is a typical example. [0003] As a kind of PLL, the digital phase-locked loop (Alldigitalphaselockedloop, ADPLL) has received more and more attention in recent years due to its good anti-interference ability, easy parameter change and convenient transfer betwe...

AI Technical Summary

Problems solved by technology

Its narrow linear region limits its phase detection range, so if there is no auxiliary circuit, the locking time of the entire loop may be longer or cannot be locked

Therefore, usually for the PLL loop, some coarse tuning loops are introduced to speed up the locking, such as the automatic frequency calibrator (AutoFrequencyCalibration, AFC), which can search and select the frequency range through the binary search method, which can expand the locking range of the loop and Shorten its lock time, but its frequency accuracy and search speed are inversely proportional

Or the analog BB-PFD can be used, so that the functions of frequency discrimination and phase discrimination can be completed without the aid of auxiliary circuits, but this may introduce new noise and reduce its portability

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