Variable-Impedance Differential Cable for Multi-Standard Signal Integrity
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Solution Overview
Problem
Information handling systems face challenges in optimizing cable impedance for different communication standards, leading to potential errors and signal integrity issues due to the need for multiple assemblies and part numbers to accommodate varying impedance requirements.
Innovation Solution
A system and method that utilize a cable with two wires, where a direct-current (DC) voltage source applies a variable DC offset voltage to one wire, adjusting the cable's impedance by altering the dielectric material's relative permittivity, allowing the impedance to be varied between 85 ohms and 100 ohms as needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a cable with fixed impedance (e.g., 92 ohms) is used to accommodate multiple communication standards, then the number of cable assemblies and part numbers is reduced, but signal integrity issues and impedance discontinuities occur
Solution Approach 1:
The patent applies the dynamics principle by making the cable impedance adjustable rather than fixed. A DC voltage source is connected to the cable to dynamically change its impedance value, allowing the same cable to be optimized for different communication standards (85-ohm for PCIe, 100-ohm for SAS) without requiring multiple cable assemblies, thus resolving the contradiction between reducing device complexity and maintaining signal integrity.
Solution Approach 2:
The patent applies the parameter changes principle by changing the electrical parameter (impedance) of the cable through application of DC voltage. By varying the DC offset voltage applied to the cable, the impedance can be adjusted between 85 ohms and 100 ohms, enabling a single cable design to serve multiple communication standards while maintaining optimal signal integrity for each standard.
2Reliability
If multiple cable types with different impedances are used to optimize each communication standard, then signal integrity is maintained, but the number of assemblies and part numbers increases
Solution Approach 1:
The patent applies the universality principle by designing a single cable assembly that can serve multiple functions - supporting both PCIe (85-ohm optimized) and SAS (100-ohm optimized) communication standards. The cable incorporates a DC voltage source that enables it to adapt its impedance characteristic based on the required communication standard, eliminating the need for separate cable types and reducing the number of assemblies and part numbers.
3Adaptability or versatility
If an approximate mean impedance (92 ohms) is used for flexible I/O ports, then compatibility with multiple interfaces is attempted, but impedance discontinuities and signal integrity issues arise
Solution Approach 1:
The patent resolves this contradiction by making the cable impedance dynamic rather than statically set to a mean value. The DC voltage source enables the cable to switch between 85-ohm and 100-ohm impedance optimization, allowing the flexible I/O port to maintain both adaptability to multiple interfaces and signal integrity by using the appropriate impedance value for each specific communication standard.
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 reduces errors and signal integrity issues by dynamically adjusting the cable impedance to match specific requirements, enhancing the compatibility and performance of information handling systems with various communication standards.
Implementation Method 1
applying a variable direct-current (DC) offset voltage to a first wire of the two wires of the cable in order to vary an impedance of the cable as a function of the variable DC offset voltage
Data Source
AI summary
A system may include a transmitter, a receiver, a cable coupled between the transmitter and the receiver and having two wires for communicating a differential signal from the transmitter to the receiver, and a direct-current (DC) voltage source coupled to a first wire of the two wires of the cable and configured to apply a variable DC offset voltage to the first wire in order to vary an impedance of the cable as a function of the variable DC offset voltage.