Tristate Output Buffer Layout to Prevent Cross Currents
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Solution Overview
Problem
Existing tristate output buffers in redundant data processing systems are susceptible to radiation-related malfunctions and voltage drops, leading to unintended cross currents and reduced reliability in outer space environments.
Innovation Solution
A tristate output buffer design featuring two or three branches, each with four individually controllable semiconductor elements, where the semiconductor elements of different types are arranged in series and controlled independently to prevent cross currents and ensure reliable voltage level detection, using majority decision units to aggregate signals and correct errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a tristate output buffer is used in redundant data processing systems, then reliability is improved, but radiation-related malfunctions and cross currents occur leading to voltage drops
Solution Approach 1:
The output buffer is divided into multiple independent branches (first branch with first buffer, second branch with second buffer). Each branch processes redundant data independently through its own semiconductor elements, allowing the system to segment the harmful effects of radiation and prevent a single point of failure from compromising the entire system.
Solution Approach 2:
Different types of semiconductor elements are used in different positions within the circuit. The first buffer contains semiconductor elements of a first type, while the second buffer contains semiconductor elements of a second type. This local differentiation ensures that cross currents cannot flow between branches even if radiation affects one particular element, as the different element types have different conduction characteristics.
2Object-generated harmful factors
If semiconductor elements are arranged in series with independent switching control, then cross currents are prevented, but device complexity increases
Solution Approach 1:
The circuit is segmented into multiple branches with series-connected semiconductor elements in each branch. By controlling each element independently, the patent prevents cross currents from flowing between the supply port and ground port, as the series arrangement requires all elements in a path to be conductive simultaneously for current to flow.
Solution Approach 2:
The semiconductor elements act as intermediaries between the supply port/ground port and the output port. Their independent switching control allows them to mediate the flow of current, enabling or blocking conduction paths as needed to prevent cross currents while maintaining the tristate functionality.
Data Source
AI summary
A tristate output buffer includes a first branch with a first buffer, and a second branch with a second buffer. The first buffer includes a supply port, a ground port, an output port, two switchable semiconductor elements of a first type, and two switchable semiconductor elements of a second type. Switching behavior of the switchable semiconductor elements of the first type differs from switching behavior of the switchable semiconductor elements of the second type. The two switchable semiconductor elements of the first type are connected in series and are between the supply port and the output port such that they can be put in a conductive state independent of each other. The two switchable semiconductor elements of the second type are connected in series and are between the ground port and the output port such that they can be put in a conductive state independent of each other.