Non-linear Spread Spectrum Clock Generator Using Linear Combinations
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Solution Overview
Problem
Existing spread spectrum clock generators face challenges in reducing electromagnetic interference (EMI) due to complex circuits, which increase chip area and reduce performance, necessitating a simpler method to generate non-linear waveform profiles.
Innovation Solution
A spread spectrum clock generator utilizing a phase locked loop with a non-linear profile generator and delta-sigma modulator to create a non-linear waveform profile through linear combinations of signals with varying slopes and initiation times, approximating a Hershey-Kiss profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If complex circuits are used to generate non-linear waveform profile signals, then electromagnetic interference reduction is improved, but device complexity and chip area increase
Solution Approach 1:
The non-linear waveform profile generation is segmented into multiple linear ramp function segments. Each segment corresponds to a specific time interval with unique slope and initiation time characteristics. By dividing the complex non-linear generation into simpler linear segments, the circuit complexity is reduced while maintaining the electromagnetic interference reduction effect.
Solution Approach 2:
The patent employs dynamic selection of linear ramp functions based on timing signals. The system dynamically switches between different linear ramp functions (with different slopes and initiation times) to construct the non-linear waveform profile. This dynamic approach allows a simple circuit to generate complex non-linear waveforms that minimize peak power and reduce electromagnetic interference.
2Object-affected harmful factors
If complex circuits are used to generate non-linear waveform profile signals, then electromagnetic interference reduction is improved, but chip area increases
Solution Approach 1:
The chip area is optimized by segmenting the waveform generation into simple linear ramp functions that can be implemented with minimal circuitry. Each linear segment requires basic circuit elements, and the segmentation allows efficient packing of the generation logic, reducing the overall chip area while maintaining the non-linear profile generation capability for EMI reduction.
Solution Approach 2:
The patent changes the approach from generating complex non-linear waveforms directly to selecting and combining linear ramp functions with varying parameters (slopes and initiation times). This parameter-based approach allows the same physical circuit to generate different non-linear profiles by changing control parameters, thereby reducing the chip area required for multiple dedicated circuits.
3Manufacturing precision
If complex circuits are used to generate non-linear waveform profile signals, then waveform accuracy is improved, but operating speed decreases
Solution Approach 1:
The system dynamically selects from pre-defined linear ramp functions based on timing control signals. This dynamic selection mechanism allows the circuit to rapidly switch between different linear segments to construct the non-linear waveform profile, maintaining high operating speed while achieving accurate non-linear waveform generation through the coordinated action of multiple simple linear functions.
Solution Approach 2:
The linear ramp functions are pre-configured with specific slopes and initiation time values during circuit design. This preliminary preparation of waveform segments allows the operating circuit to simply select and combine them according to the desired non-linear profile, avoiding complex real-time calculations and thereby maintaining high operating speed while ensuring waveform accuracy.
Data Source
AI summary
A non-linear spread spectrum clock generator using a linear combination may include a phase locked loop configured to receive a reference signal and generate an output signal according to the reference signal and a feedback signal that compensates for the output signal. The phase locked loop may include a divider configured to generate the feedback signal by dividing the output signal by a divisional ratio. The non-linear spread spectrum clock generator may include a non-linear profile generator configured to generate a non-linear signal by selectively outputting selected ones of a plurality of signals according to the absolute magnitudes of the signals and a delta-sigma modulator configured to receive the outputted linear ramp function and to change the divisional ratio. The signals may vary according to different linear ramp functions. The different ramp functions may include different slopes and initiation time values.