Processor Clock Synchronization via Local Bus Edge Detection
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Solution Overview
Problem
Current methods for synchronizing a processor clock with a bus clock in computer systems are inefficient, requiring significant design effort, prone to human error, and unable to dynamically adjust to changing clock ratios, leading to timing issues and reduced system performance.
Innovation Solution
A circuitry system that detects the leading edge of the bus clock using a previous edge detector, clock ratio controller, and flag generating circuit, allowing for local synchronization of the processor clock within the processor, eliminating the need for a centralized control signal and enabling dynamic re-synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a centralized clock control circuit is used to generate control signals for synchronizing processor clock with bus clock, then clock synchronization is achieved, but design complexity increases and human error is introduced due to manual deskew adjustments
Solution Approach 1:
The processor locally detects the leading edge of the bus clock and autonomously generates synchronization control signals without requiring a centralized clock control circuit. This self-service approach eliminates manual deskew adjustments and reduces design complexity while maintaining synchronization accuracy.
Solution Approach 2:
The clock synchronization function is extracted from the centralized clock control circuit and implemented locally within the processor. By removing the need for centralized control signal distribution and manual deskew adjustments, the system simplifies the clock control architecture while maintaining reliability.
2Reliability
If the clock ratio between processor clock and bus clock is fixed during power up, then synchronization is maintained, but adaptability to dynamic performance and power requirements is lost
Solution Approach 1:
The system enables dynamic adjustment of the clock ratio between processor clock and bus clock during operation. The processor can adaptively change the multiplication factor (e.g., from 2x to 4x or 8x) based on real-time performance requirements and power constraints, transforming a static fixed-ratio system into a dynamic adaptive system.
Solution Approach 2:
The clock ratio parameter is made variable rather than fixed. The processor dynamically changes the frequency multiplication factor to optimize performance-power tradeoffs, allowing the system to adapt to varying workload demands while maintaining proper synchronization through local leading edge detection.
3Reliability
If a PLL device is used to constantly resynchronize processor clock to bus clock, then clock synchronization is maintained, but device area and cost increase
Solution Approach 1:
The processor performs self-synchronization by locally detecting the bus clock leading edge and autonomously generating the appropriate control signals. This eliminates the need for a separate PLL device, reducing silicon chip area while maintaining reliable clock synchronization.
Solution Approach 2:
Instead of using a PLL as an intermediary device to generate and synchronize clocks, the system uses direct local detection of the bus clock leading edge within the processor. This removes the intermediate PLL component and its associated area requirements while achieving the same synchronization function.
4Productivity
If the processor operates at high clock frequency, then processing performance is enhanced, but power consumption increases
Solution Approach 1:
The processor dynamically adjusts its operating clock frequency based on real-time performance requirements and power constraints. By utilizing the local bus clock leading edge detection, the processor can flexibly change between different frequency multiplication factors (2x, 4x, 8x), enabling optimal performance-power tradeoff adjustments during operation.
Data Source
AI summary
Systems and methods for detecting a leading edge of a bus clock signal are disclosed herein. One edge detecting system includes a device for providing a bus clock and a processor clock, in which the processor clock is an integer multiple of the bus clock. The device for providing the clocks, however, does not provide a control signal that indicates the location of an edge of the bus clock. The system further includes a clock tree configured to distribute the bus clock and processor clock to multiple destinations, whereby the destinations receive the bus clock and processor clock delayed by an insertion time of the clock tree. The system also includes a processor having a device for detecting the leading edge of the bus clock delayed by the insertion time. Furthermore, a method is disclosed herein. The method includes generating a bus clock and a processor clock without a corresponding control signal, receiving an insertion-delayed version of the bus clock and processor clock, and processing the insertion-delayed bus clock and processor clock to generate a flag signal that indicates the location of a leading edge of the insertion-delayed bus clock.