QDR Host Interface Memory Buffer for Bandwidth Latency Trade-off
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Solution Overview
Problem
Current memory systems face limitations in increasing data rates and bandwidth while maintaining similar latency and capacity as existing DDR5 standards.
Innovation Solution
The implementation of a dual in-line memory module (DIMM) with a quad-data-rate (QDR) host interface, which includes conversion circuitry to buffer data between a host device and memory devices, allowing the host interface to operate at QDR while maintaining DDR data rates for DRAM devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the data rate is increased to improve bandwidth, then the bandwidth is improved, but the latency increases
Solution Approach 1:
The patent implements a write buffer that pre-fetches and stores data locally before it is needed by the memory controller. This preliminary action allows the system to prepare data in advance, enabling higher data rates without proportionally increasing latency, as the buffer can supply data immediately when needed.
Solution Approach 2:
The patent introduces a write buffer as an intermediary component between the host interface and the memory array. This buffer acts as a mediator that decouples the high-speed write operations from the lower-speed memory access operations, allowing the system to achieve high bandwidth while maintaining low latency for actual memory access.
2Productivity
If the data rate is increased to improve bandwidth, then the bandwidth is improved, but the power consumption increases
Solution Approach 1:
The write buffer pre-fetches and stores data locally before it is needed, allowing data to be prepared in advance at lower power. This reduces the need for high-power operations during actual memory access, as the buffer can supply data using lower-power read operations.
Solution Approach 2:
The write buffer serves as an intermediary that separates high-bandwidth transfer operations from power-intensive memory access operations. By buffering data locally, the system can maintain high bandwidth while reducing peak power consumption during memory access operations.
3Productivity
If the data rate is increased to improve bandwidth, then the bandwidth is improved, but the signal integrity deteriorates
Solution Approach 1:
The write buffer pre-fetches data before it is needed, allowing the system to operate at higher data rates during the pre-fetch phase when signal integrity requirements are less stringent. The buffered data can then be supplied to the memory controller at lower rates when signal integrity is more critical.
Solution Approach 2:
The write buffer acts as an intermediary that decouples high-speed data transfer from memory access operations. This allows the system to achieve high bandwidth during buffer operations while maintaining signal integrity during actual memory access, as the buffer absorbs the high-frequency signaling requirements.
Data Source
AI summary
Technologies for converting quad data rates on a host interface to double data rates on a memory interface are described. One memory module includes a data buffer device with a host-side interface circuit that sends or receives first data to and from a host device at a quad data rate and a memory-side interface circuit that sends or receives second data to and from a set of memory devices at a first specified data rate that is less than the quad data rate. The memory module includes conversion circuitry to down-convert the first data at the quad data rate to the second data at the first specified data rate and up-convert the second data at the first specified data rate to the first data at the quad data rate.