Dynamic Memory Termination Impedance Switching
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Solution Overview
Problem
Current memory systems face performance reduction due to high impedance default termination values in DDR3 I/O interfaces, leading to decreased timing and voltage margins, especially as memory speeds increase, as they fail to dynamically adjust termination impedance settings effectively.
Innovation Solution
Implementing a method and apparatus that dynamically switch between programmable finite termination impedance value settings for memory I/O interfaces in response to a termination signal level, allowing ranks not being accessed to have a first finite impedance value and ranks being accessed to transition to a second impedance value, thereby improving signal quality without transitioning to high impedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the termination impedance of unaccessed ranks is set to high impedance to save power, then power consumption is reduced, but timing and voltage margins on read signals are reduced
Solution Approach 1:
The termination impedance is made dynamically adjustable between two finite states based on access status. Unaccessed ranks use a first finite impedance value for power efficiency, while accessed ranks switch to a second finite impedance value for optimal signal quality, eliminating the need for high impedance states
Solution Approach 2:
The invention changes the termination impedance parameter from traditional high impedance (infinite) to programmable finite impedance values. This allows optimization of both power consumption and signal quality by selecting appropriate finite impedance values for different operational states
2Reliability
If the termination impedance is set to a single finite value for all ranks, then signal quality is improved, but power consumption increases due to continuous electrical path from power supply to ground
Solution Approach 1:
The termination impedance configuration is made dynamic, allowing the system to switch between different finite impedance values based on whether ranks are accessed or unaccessed. This eliminates the need for continuous power consumption while maintaining signal quality when needed
Solution Approach 2:
Different termination impedance values are applied locally to different ranks based on their access status. Accessed ranks receive optimal finite impedance for signal quality, while unaccessed ranks use a different finite impedance value that reduces power consumption
3Reliability
If the termination impedance is dynamically switched between high impedance and finite impedance, then timing and voltage margins are improved, but signal reflections occur during transitions
Solution Approach 1:
The invention changes from switching between high impedance and finite impedance to switching between two finite impedance values. This parameter change eliminates signal reflections during transitions because finite impedance values provide continuous impedance matching, preventing the reflections that occur with high impedance states
Data Source
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AI summary
Described herein are a method and an apparatus for dynamically switching between one or more finite termination impedance value settings to a memory input-output (I/O) interface of a memory in response to a termination signal level. The method comprises: setting a first termination impedance value setting for a termination unit of an input-output (I/O) interface of a memory; assigning the first termination impedance value setting to the termination unit when the memory is not being accessed; and switching from the first termination impedance value setting to a second termination impedance value setting in response to a termination signal level.