Magnetic Sensor IC Layout for Low-Noise Digital Field Output
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Solution Overview
Problem
Semiconductor magnetic field sensors typically provide analog outputs, which are impractical for high noise and high intensity magnetic field environments, and the incorporation of delta-sigma modulator-based ADCs is challenging due to noise artifacts and complexity.
Innovation Solution
An integrated circuit that includes a semiconductor magnetic field sensor coupled with a delta-sigma modulator-based ADC, providing a digital output and allowing for voltage sensing through external terminals, which reduces noise interference and enhances measurement accuracy in noisy environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an analog output is used for the magnetic field sensor, then the sensor can operate in high noise and high intensity magnetic field environments, but signal processing must be performed by a distant circuit which increases system complexity and reduces integration
Solution Approach 1:
The patent combines the magnetic field sensor and the ADC circuit onto a single integrated circuit die. The sensor output is directly coupled to the ADC input, merging the sensing function with the conversion function. This eliminates the need for external analog signal processing circuits while maintaining the ability to operate in high noise environments, as the digital output is less susceptible to interference.
Solution Approach 2:
The patent introduces a magnetic shield or isolation structure between the digital circuits and the magnetic field sensor. This intermediary element protects the sensitive sensor from magnetic field artifacts generated by the digital circuits, enabling co-integration of both functions on the same die without mutual interference.
2Ease of operation
If a delta-sigma modulator-based ADC is incorporated on the same die as the magnetic field sensor, then digital output is achieved which simplifies signal processing, but noise artifacts from digital circuits may be detected by the sensor
Solution Approach 1:
The patent introduces a magnetic shield or isolation structure between the digital circuits and the magnetic field sensor. This intermediary element protects the sensitive sensor from magnetic field artifacts generated by the digital circuits, enabling co-integration of both functions on the same die without mutual interference.
Solution Approach 2:
The patent extracts or removes the problematic magnetic field artifacts from the system by implementing careful circuit layout techniques, grounding strategies, and shielding that isolate the digital switching noise from the sensor region. This allows the ADC to function digitally while preventing its noise from affecting the analog sensor.
3Measurement precision
If analog-to-digital conversion is performed externally, then noise artifacts from ADC circuits are avoided, but the system requires additional external components and increased device complexity
Solution Approach 1:
The patent combines the magnetic field sensor and the ADC circuit onto a single integrated circuit die. The sensor output is directly coupled to the ADC input, merging the sensing function with the conversion function. This eliminates the need for external analog signal processing circuits while maintaining the ability to operate in high noise environments, as the digital output is less susceptible to interference.
Solution Approach 2:
The patent introduces a magnetic shield or isolation structure between the digital circuits and the magnetic field sensor. This intermediary element protects the sensitive sensor from magnetic field artifacts generated by the digital circuits, enabling co-integration of both functions on the same die without mutual interference.
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 enables accurate digital output measurements of magnetic field strength in high noise environments, facilitating applications in motor control, audio amplifiers, and lighting systems by minimizing noise artifacts and simplifying signal processing.
Implementation Method 1
Hall effect sensors and other semiconductor magnetic field sensors are widely used in applications in which it is desirable to provide a measurement of DC magnetic fields
Data Source
AI summary
A digital output semiconductor magnetic field sensor integrated circuit provides a low-cost and dense packaging solution for providing digital indicators of magnetic field magnitudes. A delta-sigma modulator based analog-to-digital converter (ADC) is integrated on a die with a semiconductor magnetic field sensor. The delta-sigma modulator provides for noise-shaping the sensor output and the co-location of the sensor and the converter on the die provides for improved noise immunity. The current loops of the ADC and digital interface are made as small as possible and are disposed on the die so that they are orthogonal to the axis of the magnetic field sensor, so that noise from the converter operation is isolated from the sensor.