Apparatus and method for frequency expansion of reference clock signal

Abstract

The invention provides a device for spreading spectrum of a reference clock signal and a method thereof, wherein, the device comprises a divider which is used for receiving an M value and an N value, generating a first floating point decimal according to the M value and the N value, and sending the first floating point decimal to a spread spectrum control generator; the spread spectrum control generator which is used for receiving the first floating point decimal from the divider and the reference clock signal from an analog circuit, generating a second floating point decimal for spreading the spectrum according to the first floating point decimal, the reference clock signal and modulation frequency, and sending the second floating point decimal to a delta sigma modulator; the delta sigma modulator which is used for generating a first integer distribution according to the second floating point decimal and sending the first integer distribution to the analog circuit; and the analog circuit which is used for sending the external reference clock signal to the spread spectrum control generator, generating a first frequency division clock signal according to the first integer distribution, and comparing and adjusting phases of the first frequency division clock signal, and spreading the spectrum of the reference clock signal.

Description

technical field [0001] The invention relates to the field of electronic equipment, in particular to a device and method for spreading spectrum of a reference clock signal. Background technique [0002] When an electronic system works at a single frequency, since the energy at this frequency is very high, strong electromagnetic pulse interference (Electromagnetic Interference, EMI for short) will be generated at this frequency. This electromagnetic interference can affect other electronic equipment or the human body. At present, electronic products, especially consumer electronic equipment, have very strict EMI quantification regulations to reduce EMI. At present, the basic method for reducing EMI is to reduce the energy of a specific frequency by spreading the spectrum of a clock or a signal. [0003] At present, the method of spreading the spectrum clock while utilizing the floating-point N phase-locked loop (fractional N PLL) to generate the recovered clock is to control...

AI Technical Summary

Problems solved by technology

This feature limits the number of phases that can be generated, thus limiting the accuracy of the spread spectrum

The low accuracy of the spread spectrum is not conducive to recovering the signal at the receiving end, and at the same time increases the noise of the spread spectrum clock

[0008] Second, the spread spectrum clock signal will have spurs

This spur can be very detrimental in systems that require a high quality clock signal

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