Multi-FIFO Pointer Alignment via Master Logic Clock Stop
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Solution Overview
Problem
Aligning multiple first-in, first-out (FIFO) buffers in high-speed applications is challenging due to uncertainties in pointer synchronization, which degrades performance when FIFO control signals are daisy-chained, especially in designs requiring precise timing for serializer-deserializer (SerDes) standards.
Innovation Solution
A master logic circuit generates a read clock stop signal and write reset enable signal to suspend and align write and read pointers across multiple FIFO buffers, ensuring synchronized pointer resets and alignment through a synchronized read clock stoppage and restart mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If FIFO control signals are daisy-chained to align pointers, then pointer alignment between FIFO buffers is achieved, but performance degrades in high speed applications
Solution Approach 1:
The patent introduces a global synchronization signal as an intermediary mechanism that coordinates pointer resets across all FIFO buffers simultaneously. This mediator signal eliminates the need for daisy-chained control signals and resolves the timing uncertainties that degrade performance in high-speed applications.
Solution Approach 2:
The synchronization signal serves multiple functions: it coordinates pointer alignment across all FIFO buffers, maintains timing precision, and enables high-speed operation simultaneously. This universal signal replaces the complex daisy-chain architecture with a single multi-functional control mechanism.
2Stability of the object's composition
If FIFO pointer resets are synchronized to the write/read clock domain, then pointer updates are coordinated, but uncertainty is introduced to the pointer alignment between different FIFO buffers
Solution Approach 1:
The patent separates the pointer update coordination function from the alignment precision function. Pointer updates continue to be coordinated through clock-domain synchronization, while alignment precision is achieved through the separate global synchronization signal that resets all pointers simultaneously across different FIFO buffers.
Solution Approach 2:
The global synchronization signal acts as an intermediary that bridges the gap between clock-domain coordinated updates and precise cross-buffer alignment. It provides a clean separation that allows both coordination and precision to be achieved independently without introducing uncertainty.
3Adaptability or versatility
If multiple FIFO buffers operate in synchronous but not synphase clock domains, then data transfer between operations is enabled, but alignment of pointers presents a design challenge
Solution Approach 1:
The global synchronization signal provides a universal mechanism that works across all FIFO buffers operating in different synchronous clock domains. It enables pointer alignment without requiring complex domain-specific adaptation logic, reducing overall device complexity while maintaining versatility.
Data Source
AI summary
In described embodiments, a multiple first-in, first-out buffer pointers (multi-FIFO pointers) alignment system includes synchronization circuitry to align multiple FIFO buffer operations. A FIFO read clock stoppage signal is generated by master logic that stops the read clock shared by all the transmit channels and then re-starts the read clock to align them. The FIFO read clock stoppage signal is applied to the read clock of all FIFOs which need to be aligned and, when rate change is needed, the FIFO read clock stoppage signal suspends the read clock, causing local write and read pointers to be reset. After the FIFO read clock stoppage signal is de-asserted, the read clock starts to all FIFOs concurrently, thereby aligning the channels.