Asynchronous FIFO Buffer for Memory Latency Control
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Solution Overview
Problem
As data transfer rates increase, memory devices face challenges in meeting timing specifications such as read latency due to synchronization issues between the read enable signal and data output in conventional memory devices, making it difficult to design circuitry that meets latency requirements.
Innovation Solution
The implementation of an asynchronous first-in-first-out (FIFO) buffer that provides data output within a specified latency tolerance, allowing the read clock input to be asynchronous from the write clock input, and using pre-fetching and status flags to manage data transfer efficiently, thereby decoupling the synchronization of these signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If data transfer rate is increased, then productivity is improved, but timing specification compliance deteriorates
Solution Approach 1:
The patent implements a pre-fetch mechanism that reads data from the memory array into the FIFO buffer before the read enable signal is asserted. This preliminary action ensures data is ready in advance, allowing the system to meet latency requirements even at higher data transfer rates where timing margins are tighter.
Solution Approach 2:
The patent introduces an asynchronous FIFO buffer as an intermediary component between the memory array and the output interface. This buffer decouples the timing requirements of data writing (from memory array) and data reading (to output interface), allowing independent optimization of each interface while maintaining timing specification compliance.
2Device complexity
If read clock and write clock are synchronized, then device complexity is reduced, but adaptability deteriorates
Solution Approach 1:
The patent employs asymmetric clocking where the read clock and write clock can operate independently with different phases and frequencies. The write clock is derived from the read enable signal, creating an asymmetric relationship that allows the system to adapt to varying timing requirements without complex synchronization logic.
Solution Approach 2:
The patent implements dynamic clock generation where the write clock frequency and phase are adjusted based on the read enable signal characteristics. This dynamic approach allows the system to adapt to different operating conditions and timing specifications without requiring complex predetermined synchronization schemes.
Data Source
AI summary
An asynchronous FIFO buffer that provides data in response to requests to read a memory array is disclosed. The asynchronous FIFO buffer provides the data output within a latency tolerance. The asynchronous FIFO has a read clock input and a write clock input. The read clock input receives a read enable signal that defines how data should be clocked out. The write clock input receives a write clock that is asynchronous from the read enable signal. The asynchronous FIFO inputs data from the memory array in accordance with the write clock signal. The asynchronous FIFO outputs data in accordance with the read enable signal. Control logic may pre-fetch data from the memory array into the asynchronous FIFO prior to the read enable signal first being received.