EMC Test Signal Limiting to Prevent Amplifier Overdrive

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Solution Overview

Problem

Existing EMC test systems face issues with amplifiers being overdriven due to high input signal levels, leading to non-linear amplification and potential damage, as they lack effective mechanisms to limit signal levels to prevent overdriving.

Innovation Solution

A system comprising a signal source and an amplifying unit where the signal source limits the test signal level to be below a predefined threshold value, set based on calibration data, to prevent overdriving the amplifier, ensuring linear amplification and protecting the amplifier from damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the signal source generates test signals with high signal strength for EMC testing, then the test signal level is sufficient for measurements, but the amplifier may be overdriven causing non-linear amplification and potential damage

Engineering Contradiction:
Improvetest signal strengthVSAvoidamplifier operation safety
Core Design Contradiction:
PowerVSReliability

Solution Approach 1:

The signal source performs preliminary action by limiting the output signal level before the signal reaches the amplifier. The signal source is configured to limit a level of the generated test signal which is provided to an input of the amplifying unit, preventing the amplifier from being overdriven while still providing sufficient test signal strength for EMC measurements

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system implements feedback by using calibration data stored in memory that characterizes the amplifier's input signal level requirements. The signal source uses this feedback information to automatically adjust and limit its output signal level, ensuring the amplifier operates within its linear region without requiring manual intervention

Inventive Principle:
Principle #23Feedback

2Power

If the amplifier is driven with high input signal levels to achieve sufficient output signal strength, then the test signal amplitude is adequate for EMC measurements, but the amplifier operates non-linearly producing distortion

Engineering Contradiction:
Improveoutput signal strengthVSAvoidsignal amplification linearity
Core Design Contradiction:
PowerVSManufacturing precision

Solution Approach 1:

The signal source performs preliminary action by pre-limiting the output signal level based on stored calibration data before the signal enters the amplifier. This prevents the amplifier from receiving excessive input levels that would cause non-linear operation, ensuring both sufficient output signal strength and maintained amplification linearity

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system changes the parameter of input signal level by using calibration data to determine appropriate limitation thresholds. The signal source adjusts its output signal level parameter based on the amplifier's characteristics, transforming the signal to match the amplifier's optimal operating range and preventing non-linear distortion

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3982129B1System and method for performing electromagnetic compatibility measurements
Publication Date: 2024.09.04 ROHDE & SCHWARZ GMBH & CO KG
  • EP3982129B1 patent drawingFigure 1
  • EP3982129B1 patent drawingFigure 2
  • EP3982129B1 patent drawingFigure 3

AI summary

The present invention provides a system and a method for performing electromagnetic compatibility measurements. A signal source generates a test signal which is amplified by an amplifier. Overdriving of the amplifier is prevented by limiting the test signal applied to the amplifier below a predefined threshold value.