Threshold Signal Conditioning Circuit for Wide-Range Measurement

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Solution Overview

Problem

Existing measurement devices face challenges in accurately measuring electrical signals with high dynamic ranges, as current methods either compromise on resolution, require time-consuming and resource-intensive adjustments, or struggle with stability and computational demands, especially in automotive applications where both low and high currents/voltages need to be measured.

Innovation Solution

An electrical circuit with a threshold circuit that dynamically adjusts a conditioning parameter based on the input signal, allowing for higher resolution at low values and lower resolution at high values, eliminating the need for pre-measurements and software calculations, and maintaining stability across temperature variations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a constant output slope is used for all signal values, then the measurement range covers the full ADC range, but the resolution is the same for both low and high currents resulting in poor low current performance

Engineering Contradiction:
Improvemeasurement rangeVSAvoidresolution for low currents
Core Design Contradiction:
Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent applies dynamics by making the output slope variable rather than constant. The circuit automatically adjusts the output slope based on the input signal amplitude: using a first output slope for low input values and a second output slope for high input values. This dynamic adaptation allows the system to optimize resolution for low currents while maintaining full measurement range coverage.

Inventive Principle:
Principle #15Dynamics

2Measurement precision

If different resolutions are used for low and high currents with software switching, then measurement precision is improved, but time and computing resources are required for evaluating sub-range and changing amplifier gain

Engineering Contradiction:
Improveresolution for low currentsVSAvoidtime for evaluating sub-range and changing gain
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent replaces the software-based gain switching mechanism with an analog circuit implementation. The threshold circuit and amplifier configuration automatically switch between different output slopes based on the input signal level, eliminating the need for software evaluation and gain reconfiguration. This analog approach achieves the same resolution optimization without the time and computational overhead of software control.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Adaptability or versatility

If a logarithmic amplifier is used to achieve wide range measurement, then measurement range is improved, but stability over temperature deteriorates and computing resources are required for logarithm calculations

Engineering Contradiction:
Improvemeasurement rangeVSAvoidstability over temperature
Core Design Contradiction:
Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

The patent uses simple, stable analog components (resistors, amplifiers, threshold circuits) rather than complex logarithmic amplifiers. The circuit employs basic linear components that are inherently stable over temperature, avoiding the temperature sensitivity and computational complexity of logarithmic amplification while still achieving wide dynamic range measurement through dual-slope operation.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Data Source

PatentEP4401319A1Electrical circuit of signal conditioning and measurement device
Publication Date: 2024.07.17 APTIV TECHNOLOGIES AG
  • EP4401319A1 patent drawingFigure 1~2
  • EP4401319A1 patent drawingFigure 3~4
  • EP4401319A1 patent drawingFigure 5~6

AI summary

The electrical circuit (200) is configured to condition an analog electrical input signal (Sin) into an analog electrical output signal (Sout). It comprises at least one threshold circuit (250A) configured to set a value of a conditioning parameter (mi), under control of the analog electrical input signal (Sin) and based on a corresponding electrical threshold (ISTH_A), the conditioning parameter (mi) having at least two different values (m1, m2), first and second, respectively if the analog electrical input signal (Sin) is below said corresponding electrical threshold (ISTH_A) and if the analog electrical input signal (Sin) exceeds said corresponding electrical threshold (ISTH_A).