Magnetoresistive Sensor Bridge and Amplifier for Stable Offset Output
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Solution Overview
Problem
Existing magnetoresistive sensors face challenges in providing stable and precisely defined operating parameters, such as power consumption and differential analog output voltage, especially in miniaturized camera modules like those in smartphones.
Innovation Solution
The proposed magnetoresistive sensor includes a bridge circuit with at least one magnetoresistive resistor and an amplifier circuit configured to provide a second differential analog output voltage with a value of zero at a specified non-zero magnetic field strength. This design ensures that the common-mode voltage corresponds to a specified percentage of the supply voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional magnetoresistive sensor designs are used, then the sensor can detect magnetic fields, but the operating parameters such as power consumption and differential analog output voltage are unstable and imprecise
Solution Approach 1:
The patent applies parameter changes by configuring the amplifier circuit to output a differential analog voltage with a zero value at a specific non-zero magnetic field strength (e.g., 47mT) rather than at zero field strength. This parameter transformation allows the sensor to operate optimally in applications like camera modules where a specific magnetic field offset exists, improving both measurement precision and operating stability by aligning the sensor's zero-point with the application's operating conditions
Solution Approach 2:
The patent implements feedback through the amplifier circuit that processes the bridge circuit output and provides a corrected differential analog output voltage. The amplifier circuit receives the raw sensor signal, applies gain and offset correction, and outputs a stabilized voltage that compensates for temperature drift and manufacturing variations, thereby improving both precision and reliability of the operating parameters
2Volume of moving object
If the sensor is designed for miniaturized camera modules, then the sensor size is reduced, but the measurement sensitivity and precision are compromised
Solution Approach 1:
The patent merges the bridge circuit and amplifier circuit into a single integrated sensor device, combining the magnetic field sensing function with the signal processing function in one compact unit. This integration eliminates the need for separate external amplification circuits, reducing overall sensor volume while maintaining measurement precision through on-chip signal conditioning and differential output stabilization
Solution Approach 2:
The patent changes the output voltage parameter configuration to provide a stable differential analog output with a defined zero-point at a specific magnetic field strength. This parameter optimization allows the miniaturized sensor to achieve high measurement precision by compensating for the reduced signal amplitude that typically accompanies miniaturization, maintaining sensitivity despite the smaller form factor
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 allows for stable and precisely defined operating parameters, improved measurement sensitivity, and reduced measurement errors due to temperature fluctuations, surpassing conventional sensors in these aspects.
Implementation Method 1
a bridge circuit (2), having at least one magnetoresistive resistor (14A to 14D)
Data Source
AI summary
A magnetoresistive sensor contains a bridge circuit having at least one magnetoresistive resistor, wherein the bridge circuit is configured to provide a first differential analog output voltage. The magnetoresistive sensor also contains an amplifier circuit connected downstream of the bridge circuit, wherein the amplifier circuit is configured to provide a second differential analog output voltage based on the first differential analog output voltage provided by the bridge circuit. The second differential analog output voltage has a value of zero at a specified magnetic field strength not equal to zero. A common-mode voltage associated with the second differential analog output voltage corresponds to a specified percentage of a supply voltage of the bridge circuit.