Time pulse signal forming method and system and phase-locked circuit

Abstract

The invention provides a clock pulse signal generating method, a system and a phase locked loop circuit, particularly relating to generating a frequency spreading clock pulse using the phase modulation. A first clock pulse signal having a first spectrum could generate a second clock pulse signal using the phase modulation. The phase modulation provides a phase modulation waveform based on the integral frequency modulation waveform and regulates the zooming factor for obtaining the second clock pulse signal. The phase modulation waveform is composed of one or more impulses, which could be injected into the output terminal of a phase frequency detector of the phase locked loop circuit for generating the second clock pulse signal by the impulse density modulation or impulse width modulation. The changed phase modulation technique removes the up or down expansion limitation existing in the traditional phase modulation method and has a good disturbing performance and a low cost.

Description

technical field [0001] The present invention relates to a spread spectrum clock generation technique (spread spectrum clock generation, SSCG) implemented in an electronic device, and in particular to a novel phase modulation (phase modulation, PM) method for performing SSCG, to Solve the limitation of up or down spread, and get better signal perturbation performance at low cost compared with traditional modulation methods. Background technique [0002] In a synchronous digital system, the clock signal used to drive the system is often the main source of electromagnetic interference (EMI). Due to its periodic nature, the clock signal has an unavoidably narrow frequency spectrum. In fact, a good clock signal should concentrate all energy on a single frequency and its harmonics, thus radiating energy with infinite spectral density. The actual synchronous digital system radiates electromagnetic energy in a predetermined number of narrow frequency bands spread over the clock fr...

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Problems solved by technology

When designing the circuit, in addition to the considerations of the SSCG circuit design itself, different system levels must also be considered, which complicates the circuit design of the fifth method

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