Feedback Level Shifter for Common-Mode Noise Rejection

Solution Overview

Problem

Level shifters in noisy environments, such as power systems, face interference from common mode noise, particularly asynchronous common mode noise, which causes distortion and can lead to misfire of power switches and damage to the system.

Innovation Solution

A level shifter design that incorporates feedback signals from a high voltage circuit, using galvanic isolation barriers to isolate low and high voltage circuits and detect common mode noise, allowing for accurate level shifting by refreshing differential signals and rejecting noise through regenerate logic.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If galvanic isolation barriers are used to isolate low and high voltage circuits, then safety and electrical isolation are improved, but the level shifter becomes susceptible to common mode noise interference

Engineering Contradiction:

Improveelectrical isolationVSAvoidcommon mode noise interference

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent implements a feedback mechanism where the level shifter detects common mode noise on the isolated side and generates compensating signals to cancel the noise. The feedback loop continuously monitors the noise level and adjusts the output accordingly, allowing the system to maintain accurate signal transmission despite the presence of galvanic isolation barriers.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent introduces common mode feedback circuitry as an intermediary element that mediates between the isolated high voltage side and the low voltage side. This intermediary detects the common mode noise and provides compensation signals that counteract the noise interference, effectively bridging the gap created by the galvanic isolation barriers.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If the level shifter operates in noisy power system environments, then system functionality is maintained, but signal distortion increases due to asynchronous common mode noise

Engineering Contradiction:

Improveoperation in noisy environmentsVSAvoidsignal accuracy

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The common mode feedback mechanism continuously monitors asynchronous common mode noise in power system environments and generates real-time compensation signals. This feedback loop allows the level shifter to adapt to varying noise conditions while maintaining signal accuracy, enabling reliable operation in previously hostile electromagnetic environments.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent dynamically adjusts signal parameters by introducing noise compensation signals that change in response to detected common mode noise levels. This parameter adjustment allows the level shifter to maintain signal integrity across varying environmental conditions, effectively adapting to different noise scenarios in power systems.

Inventive Principle:

Principle #35Parameter changes

3Device complexity

If traditional level shifting without feedback is used, then device complexity is reduced, but distortion from common mode noise causes system disruption and damage

Engineering Contradiction:

Improvecircuit simplicityVSAvoidsystem stability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent implements a feedback mechanism where the level shifter detects common mode noise on the isolated side and generates compensating signals to cancel the noise. The feedback loop continuously monitors the noise level and adjusts the output accordingly, allowing the system to maintain accurate signal transmission despite the presence of galvanic isolation barriers.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent introduces common mode feedback circuitry as an intermediary element that mediates between the isolated high voltage side and the low voltage side. This intermediary detects the common mode noise and provides compensation signals that counteract the noise interference, effectively bridging the gap created by the galvanic isolation barriers.

Inventive Principle:

Principle #24Intermediary (Mediator)

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

The solution effectively reduces distortion caused by asynchronous common mode noise, ensuring accurate and robust level shifting of signals, thereby preventing disruption and damage to the system.

Implementation Method 1

isolation barrier that galvanically isolates the low voltage circuit from the high voltage circuit

Methodology Applied

Scientific EffectGalvanic isolation: Electrical Impedance Tomography

Data Source

PatentUS8988128B2Level shifter having feedback signal from high voltage circuit

Publication Date: 2015.03.24 INFINEON TECHNOLOGIES AMERICAS CORP

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. The high voltage circuit is configured to receive the differential signal from the low voltage circuit 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 differential signal is provided by the low voltage circuit responsive to a feedback signal from the high voltage circuit. The feedback signal can indicate common mode noise in the level shifter. Furthermore, the low voltage circuit can be configured to refresh the differential signal responsive to the feedback signal.