Active Edge Memory Connector with Re-Driven Signals
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Solution Overview
Problem
Existing Dual In-Line Memory Module (DIMM) connectors lack integration of active circuits, leading to signal reflections, increased capacitive load, and reduced data rates due to multiple drop-off connections and long propagation delays, which hinder the achievement of high memory capacity and high-frequency data rates while also increasing system complexity and cost.
Innovation Solution
The integration of active circuits within the connector structure using rigid and flexible PCBs with re-driver chips to facilitate point-to-point connections, minimizing capacitive load and signal reflections, and enabling efficient signal propagation through bi-directional data paths with controlled impedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple memory chips are packaged in PCB substrates and connected via edge connectors with long propagation paths, then memory capacity increases, but signal reflections and capacitive load increase, reducing data rates
Solution Approach 1:
The invention segments the memory system into multiple independent point-to-point connection paths, each with its own driver and receiver. Instead of one long shared bus, each memory chip has dedicated connection paths to the controller, eliminating signal reflections and capacitive load accumulation that occur in shared bus architectures.
Solution Approach 2:
The invention introduces active circuits with re-driver chips as intermediaries in the signal path. These re-drivers receive signals from the controller, regenerate them, and forward them to memory chips, thereby eliminating signal degradation and reflections that would otherwise occur over long propagation paths through passive connectors.
2Quantity of substance
If edge connector contacts with long wire stubs are used to connect memory chips to motherboard, then memory capacity can be increased, but impedance discontinuity causes signal reflections
Solution Approach 1:
The invention extracts and eliminates the harmful wire stubs and long propagation paths from the connection architecture. By using direct point-to-point connections without extended wire stubs, the source of impedance discontinuity and signal reflections is removed entirely.
Solution Approach 2:
Instead of using passive connectors with long propagation paths that cause reflections, the invention inverts the approach by using active re-driver circuits that regenerate signals, thereby eliminating the reflection problem inherent in passive long-path connections.
3Quantity of substance
If cumulative capacitive load from multiple DRAM chips is placed on shared DQ lines, then memory capacity increases, but data rate decreases due to increased capacitive load
Solution Approach 1:
The invention segments the shared DQ line architecture into multiple independent point-to-point data paths. Each path has its own driver and receiver, so capacitive load does not accumulate across multiple chips. This allows high data rates to be maintained while supporting multiple memory chips through parallel independent paths.
Data Source
AI summary
An Active edge connector for memory modules has a base including two PCB sides and a spacer separating the sides, with driver chips mounted on each side of each side, printed wiring electrically connecting a first set of electrical signals from each of the driver chips to a mother board on which the connector is mounted, and printed wiring for electrically connecting a second set of electrical signals from each of the driver chips to a memory module inserted in the edge connector. When a group of connectors are mounted on a mother board, electrical signals arriving at the first connector are routed to its driver chips, producing re-driven signals to the next connector, and so on. A decoder circuit provides addressing signals determining the last such connector to which the signals are intended, and which prevents the signals from going to any connectors containing memories not addressed.