Clock Extraction Circuit for Spread-Spectrum Removal
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Solution Overview
Problem
In high-speed serial data transmission, acquiring a source-synchronous clock signal independent of spread spectrum information at the upstream transmitter is challenging due to compatibility issues, which complicates crystal-less applications and increases hardware costs and complexity.
Innovation Solution
A circuit and method involving a data clock recovery module and a clock extraction module to perform clock recovery and extraction, dividing frequency to obtain a de-spread clock signal with only phase information, reducing hardware complexity and improving compatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If spread spectrum is applied at the upstream transmitter to reduce EMI electromagnetic interference, then electromagnetic interference is reduced, but the clock signal carries spread spectrum information causing compatibility problems in crystal-less applications
Solution Approach 1:
The patent extracts and removes the spread spectrum information from the clock signal using a dedicated removal module. The module separates the spread spectrum component from the original clock signal, producing a clean clock signal that maintains the original frequency and phase characteristics while eliminating the spread spectrum modulation, thereby resolving compatibility issues in crystal-less applications
2Adaptability or versatility
If spread spectrum removal is implemented to improve compatibility, then compatibility in crystal-less applications is improved, but hardware complexity increases due to additional circuit modules
Solution Approach 1:
The spread spectrum removal module is designed to be universally applicable across different application scenarios. It can be integrated into various receiver architectures and works with different spread spectrum modulation types, making it a versatile solution that addresses compatibility issues without requiring multiple specialized circuits for different applications
Solution Approach 2:
The spread spectrum removal function is nested within the existing clock recovery and signal processing architecture. The removal module is positioned between the clock signal reception and the deserializer, utilizing the existing signal flow and integrating seamlessly with the clock data recovery (CDR) circuitry, thereby minimizing additional hardware complexity
3Adaptability or versatility
If a source-synchronous clock signal independent of spread spectrum is acquired, then compatibility is improved, but the difficulty of acquiring such a signal increases
Solution Approach 1:
The patent employs feedback mechanisms within the spread spectrum removal module to continuously monitor and adjust the clock signal. The module uses feedback loops to detect the presence of spread spectrum information and dynamically adjusts the signal processing to eliminate it, ensuring a clean independent clock signal is generated despite the complexity of the acquisition process
Data Source
AI summary
A circuit and a method for removing spread spectrum are provided. The circuit includes a data clock recovery module and a clock extraction module that are connected. The data clock recovery module performs clock recovery on an input signal carrying spread spectrum information to obtain a parallel clock signal and a first signal, where the parallel clock signal includes frequency information and phase information, and the first signal includes the frequency information. The clock extraction module divides a frequency of the parallel clock signal to obtain a reference clock signal; acquires a feedback clock signal based on the first signal; acquires a de-spread clock signal based on the reference clock signal and the feedback clock signal, where the de-spread clock signal includes the phase information and does not include the frequency information; and divides a frequency of the de-spread clock signal to obtain an output clock signal.