On-Module Termination Resistors for Signal Reflection Reduction
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Solution Overview
Problem
Signal reflections and noise interference in computer memory subsystems, particularly at the interface between memory devices and system logic, limit data frequency and signal integrity, especially with higher clock rates and lower power supply voltages.
Innovation Solution
Termination resistors are placed directly on or immediately adjacent the I/O pins of memory components, connected to ground, supply voltage, or reference voltage to reduce noise and signal reflections, allowing for faster signal termination and minimizing bus contention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If termination resistors are placed on the mainboard, then signal reflections are reduced, but the termination point is too far from the signal source and noise is shared between all modules
Solution Approach 1:
The patent moves the termination resistors from the mainboard dimension to the memory module dimension, specifically placing them on the substrate immediately adjacent to the I/O pins. This dimensional shift allows each module to have its own dedicated termination point close to the signal source, eliminating the shared noise problem of mainboard termination while maintaining signal integrity.
2Reliability
If on-die termination is implemented, then the termination point is closest to the signal source, but current die and package designs do not leave enough room
Solution Approach 1:
The patent introduces the substrate as an intermediary element between the die and the mainboard. By placing termination resistors on the substrate immediately adjacent to the I/O pins rather than directly on the die, it achieves near-die termination effectiveness while working within the constraints of current die and package designs that do not have enough area for on-die termination.
3Speed
If higher signal frequencies are used, then data processing speed is improved, but signal reflections and noise interference increase
Solution Approach 1:
The patent applies preliminary action by placing termination resistors immediately adjacent to the I/O pins where signals originate from the die. This preliminary termination at the source prevents signal reflections and noise from propagating through the bus, enabling higher data frequencies to be used without the harmful effects that would otherwise increase with speed.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively reduces signal reflections and noise near the source, enabling faster signal propagation and maintaining signal integrity, while being backward compatible with existing systems and allowing for dynamic termination to optimize power usage.
Implementation Method 1
termination resistors individually electrically connecting each of the data signal lines to ground, a supply voltage, or a reference voltage of the memory package so as to reduce noise and signal reflections
Data Source
AI summary
A memory module adapted for installation in an open memory socket on a mainboard of a computer. The memory module includes a substrate with an edge connector comprising pins along an edge of the substrate, and at least one memory package mounted to the substrate and containing a memory die electrically connected to input/output leads located along the perimeter of the memory package and through which data signals are transmitted to and from the memory die. Data signal lines electrically connect a plurality of the input/output leads of the memory package to a plurality of the pins of the edge connector. Termination resistors individually electrically connect each of the data signal lines to ground, a supply voltage, or a reference voltage of the memory package so as to reduce noise and signal reflections through the data signal lines.