FIFO Status Synchronizer for Single-Step Clock Crossing
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Solution Overview
Problem
Current methods for generating converged full, empty, almost full, and almost empty status of a clock-crossing First-in-First-out (FIFO) are inefficient, requiring numerous synchronizers that waste area and power, and face challenges in performance and intellectual property integration.
Innovation Solution
A synchronizer that generates FIFO status in a single step without intermediate synchronization, using comparators, AND logic, filters, and Schmitt triggers, coupled with flip-flops, to indicate the status directly from read and write pointers, applicable to any clock crossing FIFO and pointer encoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional synchronizer methods are used to generate FIFO status, then status can be generated, but area and power consumption increase significantly
Solution Approach 1:
The patent merges the status generation logic directly into the FIFO structure by using the existing read and write pointers. Instead of separate synchronizers for each status bit, the invention combines all status generation (full, empty, almost full, almost empty) into a unified approach that uses the pointer comparisons directly, eliminating redundant synchronization components and reducing overall area.
Solution Approach 2:
The invention extracts the essential status information directly from the pointer values without requiring intermediate synchronization steps. By taking out only the necessary pointer bits for comparison and generating status signals directly from these extracted values, the design eliminates the need for extensive synchronizer infrastructure while maintaining status generation reliability.
2Reliability
If traditional synchronizer methods are used to generate FIFO status, then status can be generated, but power consumption increases
Solution Approach 1:
The patent merges the status generation logic directly into the FIFO structure by using the existing read and write pointers. Instead of separate synchronizers for each status bit, the invention combines all status generation (full, empty, almost full, almost empty) into a unified approach that uses the pointer comparisons directly, eliminating redundant synchronization components and reducing overall area.
Solution Approach 2:
The invention extracts the essential status information directly from the pointer values without requiring intermediate synchronization steps. By taking out only the necessary pointer bits for comparison and generating status signals directly from these extracted values, the design eliminates the need for extensive synchronizer infrastructure while maintaining status generation reliability.
3Reliability
If multiple synchronizers are used for status generation, then status convergence can be achieved, but device complexity increases
Solution Approach 1:
The patent merges the status generation logic directly into the FIFO structure by using the existing read and write pointers. Instead of separate synchronizers for each status bit, the invention combines all status generation (full, empty, almost full, almost empty) into a unified approach that uses the pointer comparisons directly, eliminating redundant synchronization components and reducing overall area.
Solution Approach 2:
The invention performs preliminary action by pre-positioning the read and write pointers in a synchronized state through the use of gray code or Johnson code encoding. This preliminary encoding ensures that only one bit changes at a time, allowing status convergence to be achieved naturally through the pointer progression itself, rather than requiring multiple intermediate synchronizer stages.
Data Source
AI summary
A synchronizer that can generate pipeline (e.g., FIFO, LIFO) status in a single step without intermediate synchronization. The status can be an indicator of whether a pipeline is full, empty, almost full, or almost empty. The synchronizer (also referred to as a double-sync or ripple-based pipeline status synchronizer) can be used with any kind of clock crossing pipeline and all kinds of pointer encodings. The double-sync and ripple-based pipeline status synchronizers eliminate costly validation and semi-manual timing closure, suggests better performance and testability, and have lower area and power.