Spread Spectrum Clock Generation via Phase-Shifted Sequences
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Clock signals in electronic devices often suffer from strong electromagnetic interference (EMI), which existing technologies fail to adequately address through spread spectrum techniques, leading to inconsistent energy distribution and potential performance issues.
Innovation Solution
A method and apparatus for generating a spread spectrum clock by using a reference clock to create multiple output clocks with different phases, alternating between two predetermined sequences during distinct durations to distribute energy across various frequencies, thereby reducing EMI.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If spread spectrum clock generation is used to reduce EMI, then electromagnetic interference is reduced, but energy distribution becomes inconsistent
Solution Approach 1:
The patent implements dynamic frequency adjustment by switching between multiple clock signals with different phases and frequencies. The clock generation circuit dynamically selects from a plurality of clock signals based on control signals, enabling the system to adapt frequency in real-time to achieve both EMI reduction and consistent energy distribution across different operating conditions
Solution Approach 2:
The patent changes the frequency parameter of the clock signal by selecting different phase-shifted clock signals. By adjusting the frequency parameter dynamically through the selection of different clock signals from the plurality of available signals, the system achieves spread spectrum effects while maintaining consistent energy distribution characteristics
2Object-affected harmful factors
If clock signal frequency is dynamically adjusted to disperse energy, then EMI is reduced, but system complexity increases
Solution Approach 1:
The patent segments the clock generation system into multiple independent clock signals with different phases, each generated by separate delay circuits. This segmentation allows the system to switch between discrete frequency options rather than requiring continuous frequency adjustment, simplifying the overall control mechanism while achieving spread spectrum EMI reduction
Solution Approach 2:
The patent creates a multi-functional clock generation circuit that can produce multiple different clock signals from a single reference clock. The same circuit structure generates various phase-shifted clock signals that can be selectively output based on control signals, reducing the need for separate dedicated circuits for each frequency
Data Source
AI summary
A method for generating a spread spectrum clock includes the steps of providing a reference clock having a reference period; generating a plurality of output clocks respectively having different phases according to the reference clock; generating a first/second control signal according to the reference clock and a spread spectrum clock and starting a first/second duration accordingly; during the first/second duration, outputting a first/second selecting signal representing a first/second predetermined sequence according to the first/second control signal, wherein the second predetermined sequence is a substantial reversed sequence of the first predetermined sequence; and during the first/second duration, sequentially outputting some or all of the output clocks as the spread spectrum clock according to the first/second predetermined sequence.