Variable Clock Divider for Integer and Half-Step Alignment
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Solution Overview
Problem
Current clock dividers for high-speed System on Chip (SoC) designs face challenges in providing scalable and efficient clock division, particularly for integer and half-step division, with existing solutions either being non-scalable or requiring significant area overhead, and failing to maintain clock alignment at high speeds.
Innovation Solution
A high-speed clock divider capable of integer and half-step division with guaranteed alignment, designed to operate at 1 GHz or higher, using a fractional indicator to differentiate between integer and half-step divide ratios, and allowing dynamic switching of divide ratios on the fly with minimal logic gate count increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If existing clock divider implementations are used for high-speed designs, then clock division functionality is provided, but the designs are not scalable or require significant area overhead and fail to maintain clock alignment at high speeds
Solution Approach 1:
The clock divider is segmented into distinct functional units: a counter that counts input clock cycles, a comparison unit that compares the counter value against a divisor value, and an output stage that generates the divided clock signal. This segmentation allows each unit to be optimized independently for high-speed operation while maintaining overall functionality with minimal logic overhead.
Solution Approach 2:
The clock divider implements dynamic switching capability that allows the divisor value to be changed on-the-fly without requiring system reset or stalling. The design dynamically adjusts the comparison value in real-time, enabling flexible clock frequency management while maintaining alignment through synchronized update mechanisms that ensure continuous proper operation.
2Reliability
If existing clock divider implementations are used for high-speed designs, then clock division functionality is provided, but the designs fail to maintain clock alignment at high speeds
Solution Approach 1:
The clock divider incorporates feedback mechanisms where the counter continuously monitors the input clock cycles and provides feedback to the comparison unit. This feedback loop ensures that the output clock maintains precise alignment with the input clock edges, even at high speeds of 1 GHz and above, by continuously adjusting the division ratio based on the actual counted cycles.
Solution Approach 2:
The design performs preliminary initialization of the counter and comparison units to ensure proper alignment from the start of operation. The counter is pre-configured to begin counting from a defined state, and the comparison values are pre-calculated to ensure that the first output clock edge occurs at the correct time, maintaining alignment throughout subsequent high-speed operation.
3Adaptability or versatility
If existing clock divider implementations are used, then integer division is supported, but half-step division is not supported or requires separate implementations
Solution Approach 1:
The clock divider is designed as a universal circuit that can perform both integer division (N) and half-step division (N.5) using the same hardware structure. The counter and comparison unit work identically for both modes, with the only difference being the divisor value loaded into the comparison unit, eliminating the need for separate implementation circuits and reducing overall complexity.
Solution Approach 2:
The design achieves different division ratios by changing the parameter (divisor value) loaded into the comparison unit rather than changing the hardware structure. For integer division, the divisor is set to N; for half-step division, the divisor is set to N.5. This parameter-based flexibility allows the same circuit to adapt to different division requirements without increasing implementation complexity.
Data Source
AI summary
A clock divider divides a high speed input clock signal by an odd, even or fractional divide ratio. The clock divider receives a divide factor value F representative of a divide ratio N, wherein the N may be an odd or an even integer. A fractional indicator indicates a fractional divide ratio when one and an integral divide ratio when zero. A count indicator is asserted every N/2 input clock cycles when N is even. The count indicator is asserted alternately N/2 input clock cycles and then 1+N/2 input clock cycles when N is odd. The clock divider synthesizes one period of an output clock signal in response to each assertion of the count indicator for a fractional divide ratio and synthesizes one period of the output clock signal in response to two assertions of the count indicator for an integral divide ratio.