Spread Spectrum Clock Generator for Multi-Mode PLL Conversion
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Solution Overview
Problem
Current one-chip phase locked loop (PLL) ICs available in the market do not easily support the upper-spread mode, making it difficult to generate spread spectrum clock signals in all required modes (upper-spread, down-spread, and center-spread) for devices like bit error rate measurement devices, leading to increased costs and operational challenges.
Innovation Solution
A spread spectrum clock generator with a control unit that shifts and corrects carrier frequencies and modulation factors using specific calculation expressions to generate spread spectrum clock signals in any of the upper-spread, down-spread, or center-spread modes, allowing for pseudo mode conversions between these modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a commercial one-chip PLL IC is used to generate spread spectrum clock signals, then the device is easy to acquire and cost-effective, but it cannot easily support the upper-spread mode which is required for certain measurement devices
Solution Approach 1:
The patent implements a universal spread spectrum clock generator that can operate in multiple spread modes (upper-spread, down-spread, and center-spread) using a single device. The control unit is configured to generate different modulation signals that enable the system to adapt to various spread modes, making the device versatile enough to replace multiple specialized components while maintaining ease of acquisition and cost-effectiveness
2Adaptability or versatility
If the carrier frequency is shifted to generate spread spectrum clock signals in different spread modes, then the adaptability to various modes is improved, but the complexity of frequency control increases
Solution Approach 1:
The patent employs parameter changes by systematically adjusting the carrier frequency according to specific calculation expressions for each spread mode. The control unit modifies the carrier frequency parameter based on predetermined formulas, enabling transitions between upper-spread, down-spread, and center-spread modes. This approach maintains relatively simple control logic by relying on mathematical relationships rather than complex control mechanisms
3Reliability
If a pattern generator is designed to support all spread modes for margin testing, then the measurement capability is improved, but the device complexity and cost increase
Solution Approach 1:
The pattern generator is designed with universal functionality to support all spread modes through a single integrated device. The control unit generates appropriate modulation signals that enable the pattern generator to work with upper-spread, down-spread, and center-spread clock signals. This multi-functional design maintains measurement capability while avoiding the need for multiple specialized devices, thereby controlling complexity and cost
Data Source
AI summary
Provided is a technique that can generate a spread spectrum clock signal in all of an upper-spread mode, a down-spread mode, and a center-spread mode. A spread spectrum clock generator (2) spreads a spectrum of a signal with a predetermined carrier frequency to generate a spread spectrum clock signal under the control of a control unit (13). The control unit includes carrier frequency correction control means (13b). The carrier frequency correction control means shifts the predetermined carrier frequency to generate, from one spread mode, a spread spectrum clock signal of another pseudo spread mode.