Bidirectional Capacitive Level Shifter for Asynchronous Noise
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Solution Overview
Problem
Existing level shifters face challenges in accurately shifting signals between circuits with different grounds due to exposure to common mode noise, particularly asynchronous common mode noise, which can cause distortion, disruption, and damage by interfering with the level shifting process.
Innovation Solution
A level shifter utilizing bidirectional signaling through a capacitive isolation barrier, where a low voltage circuit provides a differential signal to a high voltage circuit, and the high voltage circuit provides feedback through the same isolation barrier, allowing for galvanic isolation while avoiding a dedicated isolation barrier for feedback, thus reducing cost and footprint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dedicated level shifter and isolation barrier are utilized for the feedback signal, then signal accuracy and isolation are improved, but device complexity and cost increase
Solution Approach 1:
The patent combines the forward signal path and feedback signal path into a single isolation barrier, eliminating the need for a dedicated feedback isolation barrier. The level shifter circuit handles both bidirectional signaling and feedback through the same isolation interface, reducing component count and overall system complexity while maintaining signal accuracy.
Solution Approach 2:
The isolation barrier is designed to handle multiple functions simultaneously: forward signal transmission, feedback signal transmission, and galvanic isolation. This multi-functional approach eliminates the need for separate dedicated components for each function, reducing device complexity while maintaining reliability.
2Reliability
If a dedicated isolation barrier is used for feedback signaling, then isolation performance is improved, but cost and footprint increase
Solution Approach 1:
The patent merges the feedback isolation barrier with the main isolation barrier into a single component. This consolidation reduces the total number of isolation barriers required, lowering component costs and reducing the overall footprint of the circuit while maintaining adequate isolation performance for both forward and feedback signals.
3Device complexity
If traditional level shifting approaches are used, then circuit simplicity is maintained, but susceptibility to common mode noise increases
Solution Approach 1:
The patent introduces a capacitive isolation barrier as an intermediary between circuits with different ground references. This intermediary provides galvanic isolation that blocks common mode noise while still allowing signal transmission, protecting the circuit from noise without significantly increasing complexity.
Solution Approach 2:
The patent implements feedback signaling through the isolation barrier to enable the receiving circuit to compensate for noise and distortion. By feeding back information about the signal condition, the system can actively correct for common mode noise effects, improving noise immunity while maintaining circuit simplicity.
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 solution effectively reduces distortion caused by common mode noise, maintains accurate signal shifting, and prevents damage by utilizing bidirectional signaling to manage asynchronous common mode noise, ensuring reliable operation and cost-effectiveness.
Implementation Method 1
A low voltage circuit is configured to provide a differential signal to a high voltage circuit through a capacitive isolation barrier
Data Source
AI summary
According to an exemplary implementation, a level shifter includes a low voltage circuit and a high voltage circuit. The low voltage circuit is configured to provide a differential signal to the high voltage circuit through a capacitive isolation barrier. The high voltage circuit is configured to receive the differential signal from the low voltage circuit through the capacitive isolation barrier so as to level shift the differential signal from a first ground of the low voltage circuit to a second ground of the high voltage circuit. The high voltage circuit is further configured to provide a feedback signal to the low voltage circuit through the capacitive isolation barrier. The low voltage circuit can be configured to receive the feedback signal from the low voltage circuit between edges of the differential signal.