Spread-Spectrum Clock Generator With Feedback Phase Boundary Control
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Solution Overview
Problem
Traditional spread-spectrum clock signals for data transmission face challenges in maintaining data alignment and reliability due to uncontrollable phase relationships, leading to potential data loss or repeated readings at the receiver.
Innovation Solution
A method and circuit for generating spread-spectrum synchronous clock signals using a frequency locked loop, which compares an input signal with a feedback signal to generate control signals, introduces phase delays, and synthesizes a periodic signal to maintain the second frequency within a broadened boundary of the first frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional spread-spectrum clock signals are used for data transmission, then resistance to interference and noise is improved, but phase control becomes uncontrollable leading to data alignment issues
Solution Approach 1:
The patent employs a feedback mechanism where the spread-spectrum modulated clock signal is fed back to a frequency detector that compares it with the original clock signal. This feedback loop enables continuous monitoring and adjustment of phase relationships, ensuring that phase deviations remain within controllable boundaries while maintaining the interference-resistant properties of spread-spectrum signaling.
Solution Approach 2:
The patent modifies the spread-spectrum modulation parameters by introducing controlled phase shifts through register delays. By adjusting the fraction part of the control word and introducing n levels of phase delays, the system changes the phase parameters dynamically while maintaining synchronization, thus achieving both interference resistance and phase controllability.
2Loss of energy
If spread-spectrum modulation is applied to clock signals, then power flux density is limited, but data alignment and establishing time cannot be ensured at the receiver
Solution Approach 1:
The feedback loop continuously monitors the phase relationship between the modulated and original clock signals, enabling the system to maintain data alignment precision even with spread-spectrum modulation. The frequency detector ensures that establishing time and maintaining time requirements are met by keeping phase deviations within acceptable boundaries.
Solution Approach 2:
The patent introduces dynamic phase adjustment capabilities through register delays and fractional control words. This allows the system to adaptively maintain data alignment precision under spread-spectrum modulation by dynamically adjusting phase relationships rather than using fixed phase shifts.
3Productivity
If strong driving power is used in clock circuit, then data transmission capability is improved, but electromagnetic interference increases
Solution Approach 1:
The patent applies spread-spectrum modulation to the clock signal, which spreads the power spectral density over a wider frequency range. This reduces peak power flux density and electromagnetic interference while maintaining the strong driving capability needed for data transmission through the controlled modulation process.
Solution Approach 2:
The patent converts the potentially harmful strong radiated energy from the clock circuit into a beneficial spread-spectrum signal. By intentionally modulating the clock signal with spread-spectrum techniques, the strong driving power is transformed into a signal that maintains transmission capability while reducing electromagnetic interference through spectral spreading.
Data Source
AI summary
A method for generating spread-spectrum synchronous clock signals includes comparing an input signal of a first frequency with a feedback signal of a second frequency in a loop of feedback; generating a first control signal and a second control signal; determining an integer part I of a control word F to track the first frequency; registering n levels for the first control signal and the second control signal to introduce n phase delays for randomly changing a fraction part r (0<r<1) of the control word F to provide a broadened boundary in frequency spectrum; and generating a synthesized periodic signal with the second frequency based on a base time unit Δ, the first frequency, and the control word F, the synthesized periodic signal being fed back as the feedback signal in the loop of feedback and outputted with the second frequency being locked within the broadened boundary.