Pipelined Output Latching for Synchronous Memory Arrays
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Solution Overview
Problem
Conventional memory systems face limitations in achieving higher transaction rates due to clock delays and increased access delay times, which are exacerbated by the need for multiple registers in output register chains, hindering the improvement of clock frequency and memory access cycle time.
Innovation Solution
The implementation of a pipelined output latching system with reduced register count and optimized clock alignment using Delayed Lock Loop (DLL) or Phase Locked Loop (PLL) circuits to align data outputs with external clock edges, allowing for flexible read latency settings from 1.0 to 3.0, thereby minimizing clock cycle time and maximizing transaction rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple registers are used in output register chains to achieve flexible read latency settings, then read latency flexibility is improved, but device complexity and access delay time increase
Solution Approach 1:
The patent implements dynamic read latency control by using a select signal that can be changed to switch between different read latency modes (RL=1, RL=2, RL=3) without requiring physical reconfiguration of the register chain. The same register chain structure is dynamically adapted to provide different latency values through control signaling, resolving the contradiction between flexibility and complexity.
Solution Approach 2:
The output register chain is designed to serve multiple functions: it provides data output buffering, implements different read latency values (1, 2, or 3 clock cycles), and supports both single data rate and double data rate modes. This multi-functionality eliminates the need for separate register chains for each latency value, reducing overall device complexity while maintaining flexibility.
2Productivity
If clock frequency is increased to improve transaction rate, then productivity is improved, but access delay time and clock alignment difficulties increase
Solution Approach 1:
The patent uses a Delayed Lock Loop (DLL) circuit to pre-align the output clock edges with the external clock edges before data output. This preliminary clock alignment ensures that data is ready at the correct time relative to the external clock, allowing the memory to operate at higher clock frequencies without increasing access delay time. The DLL circuit proactively compensates for timing mismatches, enabling higher productivity.
3Manufacturing precision
If read latency is increased to allow slower access time, then manufacturing precision requirements are reduced, but loss of time increases
Solution Approach 1:
The patent segments the memory access cycle into distinct phases by using multiple register stages in the output chain. Each register stage corresponds to a specific clock cycle delay, allowing the memory to provide precise control over access time (1, 2, or 3 cycles) while maintaining stable data output. This segmentation enables flexible access time configuration without compromising manufacturing precision, as each stage can be independently optimized.
Data Source
AI summary
Systems and methods of synchronous memories and synchronous memory operation are disclosed. According to one illustrative implementation, a memory device is disclosed comprising memory circuitry having a memory output, the memory circuitry including a sense amplifier having a first output and a second output, a first data path coupled to the first output of the sense amplifier, the first data path including 2 latches/registers, and a second data path coupled to the second output of the sense amplifier, the second data path including a plurality latches/registers. In further implementations, various control circuitry, connections and control signals may be utilized to operate the latches/registers in the first and second data paths according to specified configurations, control, modes, latency and/or timing domain information, to achieve, for example, pipelined output latching and/or double data rate output.