Magnetoresistive Sensor Bridge Circuit for Noise Reduction
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Solution Overview
Problem
Existing magnetoresistive (MR) sensors struggle to simultaneously reduce 1/f noise and white noise, with previous techniques focusing only on noise reduction from the sensors themselves and not addressing system noise, and requiring complex microfabrication for parallel connection of magnetoresistive elements.
Innovation Solution
A magnetoresistive sensor design featuring a bridge circuit with four magnetoresistive elements connected in parallel, with outputs connected in parallel to an amplifier circuit, and additional configurations such as parallel connection of preamplifiers and use of set/reset circuits to reduce thermal and voltage noise, respectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If magnetoresistive elements are connected in parallel to reduce thermal noise, then thermal noise is reduced, but the manufacturing complexity increases due to complex microfabrication requirements
Solution Approach 1:
The sensor is divided into multiple magnetoresistive elements (first, second, third, and fourth elements) arranged in a bridge circuit configuration. Each element is independently fabricated using standard processes, avoiding the need for complex parallel connection microfabrication while achieving noise reduction through the segmented structure.
Solution Approach 2:
A bridge circuit is introduced as an intermediary structure that connects the magnetoresistive elements. This bridge circuit configuration enables noise reduction through differential measurement without requiring direct parallel connection of the elements, thereby simplifying the manufacturing process while maintaining the thermal noise reduction benefit.
2Object-affected harmful factors
If preamplifiers are connected in parallel to reduce voltage noise, then voltage noise is reduced, but the device complexity and circuit design difficulty increase
Solution Approach 1:
A differential amplifier is used as an intermediary that processes the differential output from the bridge circuit. This differential amplifier configuration reduces voltage noise through differential amplification without requiring multiple parallel preamplifier connections, thereby simplifying the circuit design while achieving voltage noise reduction.
Solution Approach 2:
The bridge circuit configuration provides inherent feedback mechanisms where the output from one arm of the bridge is compared against the other arms. This feedback structure enables noise cancellation and reduction without requiring additional parallel preamplifier stages, reducing circuit complexity while maintaining voltage noise reduction performance.
3Object-affected harmful factors
If complex noise reduction techniques are applied to MR sensors, then sensor noise is reduced, but system noise (including preamplifier noise) remains unchanged
Solution Approach 1:
The invention merges the noise reduction functions for both the sensor and the readout circuitry into a single integrated bridge circuit configuration. By combining the magnetoresistive elements and the differential amplification in one unified structure, both sensor noise and preamplifier noise are reduced simultaneously, improving overall system noise performance rather than just sensor noise in isolation.
Solution Approach 2:
The bridge circuit serves multiple functions simultaneously: it acts as the sensor structure, provides differential signal amplification, reduces thermal noise through its configuration, and reduces voltage noise through the differential readout. This multi-functional design addresses both sensor noise and system noise without requiring separate noise reduction techniques for each component.
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 configuration effectively reduces thermal and voltage noise, achieving improved sensitivity for biomagnetic field detection by integrating noise reduction across both the sensor and operation circuit components.
Implementation Method 1
Magnetic resistance (hereinafter, abbreviated as MR) sensors are inexpensive, small, and highly sensitive
Implementation Method 2
outputs of the respective magnetoresistive sensor parts are connected in parallel to one another to an input of an amplifier circuit
Implementation Method 3
outputs of the respective magnetoresistive sensor parts are connected in parallel to one another to an input of an amplifier circuit
Data Source
AI summary
An object of the invention is to reduce 1/f noise and white noise at the same time by integrally reducing noise of an MR sensor and noise of an operation circuit part. A magnetoresistive sensor according to the invention includes a plurality of magnetoresistive sensor parts each having a bridge circuit in which four magnetoresistive elements are connected, and outputs of the respective magnetoresistive sensor parts are connected in parallel to one another to an input of an amplifier circuit (see FIG. 2).