Closed-Loop PCB Bus Layout for Signal Reflection Mitigation
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Solution Overview
Problem
Conventional signal reflection mitigation systems in integrated circuits (ICs) connected on a Printed Wiring Board (PWB) require termination resistors to prevent voltage overshoot and undershoot, which increases size, weight, and component count, especially in applications like aircraft systems.
Innovation Solution
A closed loop bus line configuration without termination resistors is used, where integrated circuits are connected in a U-shape with a closure line within an interior layer of the PCB, preventing signal reflections and reducing overshoot and undershoot voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If termination resistors are used to reduce signal reflections, then signal integrity is improved, but circuit size, weight, and component count increase
Solution Approach 1:
The patent extracts and eliminates the termination resistors from the circuit design by implementing a closed-loop bus topology. The signal path is configured to return to the source through a different route, removing the need for traditional end-termination resistors that would otherwise be required to prevent reflections.
Solution Approach 2:
The patent transitions from a traditional linear bus topology to a closed-loop topology, adding a dimensional aspect to the signal path. The signal can travel in multiple directions around the loop, effectively creating a multi-dimensional signal propagation path that eliminates the need for endpoint terminations.
2Reliability
If termination resistors are used to reduce signal reflections, then signal integrity is improved, but device complexity increases
Solution Approach 1:
The patent removes termination resistors and associated termination logic from the circuit design. By extracting these components and replacing them with a closed-loop topology, the overall device complexity is reduced while maintaining signal integrity through the alternative signal path configuration.
Solution Approach 2:
The patent merges the signal transmission path into a continuous closed loop, eliminating the need for separate termination components at each end. This consolidation of the signal path into a unified loop structure simplifies the overall circuit architecture.
3Reliability
If termination resistors are used to reduce signal reflections, then voltage overshoot and undershoot are reduced, but size and component count increase
Solution Approach 1:
The patent extracts termination resistors from the circuit design and replaces them with a closed-loop bus topology. This elimination of discrete termination components reduces the overall circuit area while maintaining voltage stability through the continuous signal path that prevents reflections.
4Reliability
If termination resistors are used to reduce signal reflections, then signal integrity is improved, but weight increases
Solution Approach 1:
The patent extracts and removes termination resistors from the circuit design by implementing a closed-loop bus topology. This elimination of discrete components directly reduces circuit weight while maintaining signal integrity through the alternative signal path configuration.
Data Source
Figure 1A~1B
Figure 2A
Figure 2B~2C
AI summary
A circuit can include a closed loop bus line (101) having a plurality of connections. The circuit can include a plurality of integrated circuits (103, 103b, 103c, 103d, 105) disposed on the close loop bus line at a respective connection of the plurality of connections. One or more of the integrated circuits can be configured to drive a signal on the closed loop bus line. The closed loop bus line can be configured to prevent signal reflection. For example, in certain embodiments, there are no termination resistors at any of the terminations to reduce size, weight, and/or part count of the circuit.