Phase-locked loop circuit and corresponding frequency translation method

Abstract

The invention relates to a phase-locked loop, which comprises a phase discriminator, a filter, a voltage controlled oscillator and an M multiple frequency divider, wherein a reference frequency is inputted by one input end of the phase discriminator, and the output end of the M multiple frequency divider outputs a needed channel frequency; the phase-locked loop further comprises an N / N+1 multiple frequency divider and an N / N+1 multiple frequency division controller, the N / N+1 multiple frequency divider is arranged between the phase discriminator and the voltage controlled oscillator, one input end of the N / N+1multiple frequency divider is connected with the voltage controlled oscillator, the output end of the N / N+1 multiple frequency divider is connected with the other input end of the phase discriminator, and the other input end of the N / N+1 multiple frequency divider is used to receive control signal generated by the N / N+1 multiple frequency division controller, so that in one working period, the N / N+1 multiple frequency divider can output the multiple of N during the first time period and the multiple of N+1 during the second time period.

Description

technical field [0001] The invention relates to a phase-locked loop circuit (Fractional Phase-Locked Loop, PLL) and its corresponding frequency conversion method, in particular to a method capable of accurately converting the frequency of the phase-locked loop circuit. Background technique [0002] Digital Television (Digital Television) is a television system developed to provide a strong theater atmosphere at home. Compared with the widely used analog TV, it greatly improves the clarity and width of the picture, and provides CD (Compact Disc) level multi-channel audio. For digital TV, countries such as the United States, Europe, and Japan are developing their own broadcasting standards and specifications. For example, the United States adopts the Vestigial Sideband (Vestigial Sideband, VSB) system. For details, please refer to the VSB Modem Subsystem Design for Grand Alliance published in August 1995 by Wayne et al. in the document IEEE Transactions on Consumer Electronic...

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