A spread spectrum device, a method for generating a spread spectrum clock signal, and a digital circuit system

Abstract

The invention discloses a spread spectrum device, a method for generating a spread spectrum clock signal and a digital circuit system. The device includes: an interference detection circuit module, which is used to detect an electromagnetic interference signal output by at least one electromagnetic interference source in the digital circuit system. The detected electromagnetic interference signal generates an adjustment signal and outputs it to the spread spectrum circuit module; the voltage value of the adjustment signal represents the electromagnetic interference signal strength of the electromagnetic interference source to the digital circuit system; the spread spectrum circuit module is used to receive the output of the interference detection circuit module The adjustment signal is used to control the frequency bandwidth of the spread spectrum clock signal by using the voltage value of the adjustment signal, and output the spread spectrum clock signal. In the present invention, when the system EMI is large, the spread spectrum clock signal swings in a wider frequency range, so that the EMI is better suppressed; when the system EMI is small, the spread spectrum clock signal swings in a narrower frequency range, so that The frequency jitter of the spread spectrum clock signal has little impact on system reliability.

Description

technical field [0001] The invention relates to spread spectrum technology, in particular to a spread spectrum device, a method for generating a spread spectrum clock signal and a digital circuit system. Background technique [0002] Spread spectrum clock technology can effectively suppress the electromagnetic interference (EMI) generated when electronic products are working. Spread spectrum technology is an effective EMI suppression method. The principle is to disperse the energy of a single frequency point to a certain Energy within a spread spectrum range, thereby reducing the peak energy of a single point, making interference test results smaller. [0003] However, because the frequency of the spread-spectrum clock signal (hereinafter referred to as the spread-spectrum clock signal) will drift within a certain range, that is, clock jitter will be generated. Change, this kind of clock jitter, when it is serious, will have a negative impact on the reliability of the digit...

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Problems solved by technology

[0005] The inventor found in the process of realizing the present invention that, once the above-mentioned existing spread spectrum circuit has determined the width and amplitude of the spread spectrum, no matter what the size of the EMI is, it will produce the same spread spectrum clock signal, that is to say, its jitter The characteristics are fixed. In fact, for the digital circuit system, in the case of small EMI (such as when the mobile phone terminal is in standby), in order to ensure the reliability of the digital circuit system, the spread spectrum range (amplitude and width) is required Small or even no spread spectrum, the existing spread spectrum circuit design obviously cannot meet this requirement

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