DRAM Command Address Bus Stress Patterns for Parity Integrity
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Solution Overview
Problem
Existing DRAM systems face challenges in ensuring command address bus integrity during idle periods and transitions, leading to potential bit flips and misinterpretation of commands.
Innovation Solution
Implementing link stress patterns on command address (CA) links during pre-operating states of DRAM devices, using a memory controller to assert specific bit patterns over multiple clock cycles and monitor for parity errors, ensuring CA bus integrity through CA parity circuitry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the DRAM device remains in idle periods without validation procedures, then the system operates with simpler control logic, but command address bus integrity deteriorates due to potential bit flips and undetected errors
Solution Approach 1:
The patent applies preliminary action by performing validation procedures during idle periods before the DRAM device enters pre-operating states. Link stress patterns are asserted on CA links during these idle periods to proactively detect and prevent bit flips before they affect command execution, ensuring bus integrity without adding complexity to active operation control logic
Solution Approach 2:
The validation procedure utilizes the DRAM device's own CA bus parity circuitry to detect errors during idle periods. The system self-monitors its own command address bus integrity using existing hardware resources without requiring external validation equipment or complex control logic modifications
2Reliability
If validation procedures are performed during idle periods, then command address bus integrity is improved, but the system experiences increased operational complexity and potential performance overhead
Solution Approach 1:
The patent applies partial action by performing validation procedures only during idle periods when the DRAM device is not actively processing commands. Link stress patterns are asserted selectively during these non-critical time windows, providing sufficient validation coverage without interfering with normal operation or requiring continuous validation overhead
Solution Approach 2:
Validation procedures are implemented as periodic actions during idle periods between operational states. The system transitions to pre-operating states where link stress patterns are asserted for a defined duration, then returns to normal operation, creating a periodic validation rhythm that maintains integrity without continuous overhead
3Measurement precision
If link stress patterns are asserted during pre-operating states, then bit flip detection capability is improved, but the testing duration and system idle time increase
Solution Approach 1:
The patent applies continuity of useful action by asserting link stress patterns continuously during the entire pre-operating state duration. Rather than intermittent sampling, the validation procedure maintains continuous monitoring of CA links throughout the transition period, maximizing detection capability without requiring extended total testing time across multiple operational cycles
Data Source
AI summary
Embodiments herein describe link stress patterns to ensure command address bus integrity. In an example, a memory controller asserts a link stress pattern of bits on command address (CA) links of a CA bus of a dynamic random-access memory (DRAM) device, while the DRAM device is in a pre-operating state in which the DRAM device does not recognize memory access commands and in which a CA bus parity circuit of the DRAM device is enabled, where the link stress pattern of bits extends over multiple clock cycles of the DRAM device. The memory controller also monitors an error output of the DRAM device for parity errors, while asserting the link stress pattern of bits on the CA links.