DIMM Command/Address Inversion Using Strap Pins for Signal Integrity
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Solution Overview
Problem
Current memory devices face challenges in maintaining signal integrity and reducing power consumption due to increased data rates, particularly in dual in-line memory modules (DIMMs), where long interconnection stubs and suboptimal signal routing lead to limitations in mirroring command/address signals, and existing methods require complex host memory controller operations.
Innovation Solution
Implementing command/address signal mirroring or inversion techniques using strap pins to swap or invert command/address signals within memory devices, allowing for reduced stub lengths and improved signal integrity, with logic circuits determining whether to mirror or invert signals based on strap pin connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If command/address signals are transmitted at increased frequencies to achieve higher data rates, then productivity is improved, but signal integrity deteriorates due to long interconnection stubs
Solution Approach 1:
The command/address signal routing is segmented into multiple paths through the use of mirror packages and stub minimization. By dividing the signal path and using multiple access ports, the effective stub length is reduced, allowing higher frequencies to be transmitted without degrading signal integrity.
Solution Approach 2:
The patent utilizes the physical dimension of the DIMM package by implementing mirror packages on opposite sides of the module. This spatial arrangement allows command/address signals to access memory devices from multiple directions, effectively reducing the electrical stub length while maintaining high data rates.
2Ease of manufacture
If command/address signals are routed through long interconnection stubs to reach memory devices, then ease of manufacture is improved, but signal integrity deteriorates
Solution Approach 1:
The patent employs asymmetric signal routing where command/address signals are distributed to mirror packages on opposite sides of the DIMM through optimized trace routing. This asymmetric arrangement minimizes stub lengths on each side while maintaining manufacturing feasibility through standardized PCB routing techniques.
3Reliability
If mirroring techniques are implemented to reduce stub lengths, then signal integrity is improved, but device complexity increases
Solution Approach 1:
The patent implements mirror packages that are physical copies of the same memory device type on opposite sides of the DIMM. This copying approach allows identical signal routing patterns to be used on both sides, simplifying the overall design while achieving stub minimization and improved signal integrity.
Solution Approach 2:
The mirror package structure serves multiple functions simultaneously: it reduces stub lengths for signal integrity, enables higher data rates, and provides flexibility for different memory device configurations. The same physical package design can accommodate various memory device types and densities.
4Adaptability or versatility
If strap pins are used to control mirroring and inversion, then adaptability is improved, but ease of operation deteriorates due to complex configuration
Solution Approach 1:
The memory device automatically detects the configuration state through the strap pin connection status and self-configures the mirroring and inversion behavior. This self-service approach eliminates the need for manual configuration by the user, reducing operational complexity while maintaining adaptability.
Solution Approach 2:
The strap pin provides feedback information about the desired configuration state to the memory device logic. Based on this feedback, the device automatically adjusts its signal interpretation and mirroring behavior, enabling flexible configuration without requiring complex user input or external control.
Data Source
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AI summary
Examples include techniques to invert a command/address or interpret command/address logic as inverted at a memory device. A memory device located on a dual in-line memory module (DIMM) may include circuitry having logic capable of receiving a command/address signal and interpret the command/address logic indicated in the command/address signal as inverted or not based on a strap pin of the memory device.