Multi-Phase Prime Divider Circuit for High-Speed Timing Margins
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Solution Overview
Problem
Frequency dividers in data communications systems face speed bottlenecks as system clock frequencies increase, particularly when handling prime number division ratios, due to reduced timing margins in the divider loop.
Innovation Solution
A frequency divider device is designed with a multi-phase clock generator, phase-switching multiplexer circuit, and counter circuit, which generates staggered and reduced-frequency multi-phase clock signals, allowing for prime number division ratios and accommodating a range of frequencies by modulating the input clock signal through phase shifting and duty cycle adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the system clock frequency is increased to support higher data rates, then the data communication speed is improved, but the timing margin in the divider loop is reduced causing speed bottlenecks
Solution Approach 1:
The frequency divider is segmented into multiple functional blocks: a multi-phase clock generator that creates N phase-shifted clock signals, a multiplexer that selects between phases, and a counter that performs the actual division. This segmentation allows the critical division operation to occur at lower effective frequencies while the multi-phase approach distributes the high-frequency sampling across multiple phases, resolving the timing margin constraint.
Solution Approach 2:
A multiplexer is introduced as an intermediary component between the high-frequency system clock and the division counter. The multiplexer selects from N different phase-shifted clock signals, effectively mediating the transition from high-frequency input to lower-frequency division operations, thereby preserving timing margins while supporting high data rates.
2Adaptability or versatility
If a conventional frequency divider is used to achieve prime number division ratios, then the division functionality is provided, but the operational frequency range is limited due to timing constraints
Solution Approach 1:
The system dynamically switches between N different phase-shifted clock signals based on the required division ratio. By changing which phase is selected by the multiplexer and how the counter is configured, the system can adapt to different prime number division ratios while maintaining adequate timing margins, thus expanding the operational frequency range for prime number divisions.
Solution Approach 2:
The frequency divider is designed with universal functionality to handle both prime and non-prime division ratios through the same architectural structure. The combination of multi-phase clock generation, multiplexer selection, and configurable counter allows a single device to perform diverse division functions across a wide frequency range, eliminating the need for specialized circuits for different division types.
3Reliability
If the divider loop timing margin is increased to maintain reliability at high frequencies, then the timing requirements are satisfied, but the data rate is reduced
Solution Approach 1:
The system employs periodic sampling of the input clock signal through N different phases. Instead of requiring the entire division operation to complete within a single clock period at high frequency, the multi-phase approach distributes the sampling across N periodic phases, effectively increasing the timing margin available for each individual sampling operation while maintaining the high overall data rate.
Data Source
AI summary
A device is provided that includes a counter circuit configured to count cycles of an input clock signal and to generate an output clock signal periodically based on a cycle count of the input clock signal; a multi-phase clock generator configured to generate a plurality of multi-phase clock signals from a system clock signal; a multiplexer circuit coupled to the multi-phase clock generator and configured to provide a multi-phase clock signal selected from the plurality of multi-phase clock signals to the counter circuit as the input clock signal; and a selection circuit configured to provide a selection signal to the multiplexer circuit periodically to switch the multi-phase clock signal provided to the counter circuit from a current multi-phase clock signal to a next multi-phase clock signal selected from the plurality of multi-phase clock signals.