Hall Effect Sensor Offset Reduction via Extraction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Hall Effect sensors face accuracy issues due to offset voltage, which requires high dynamic range in front-end and backend circuitry, leading to increased cost and power consumption, particularly in portable devices.
Innovation Solution
A Hall Effect sensor circuit with cancellation voltage sources and a switch matrix that reduces offset voltage by selectively connecting inputs to ground or through capacitors and resistors, allowing for reduced dynamic range processing and lower power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If spinning current technique is used to reduce offset voltage effects, then measurement precision is improved, but device complexity and power consumption increase due to heavy burden on front end amplifier and ADC
Solution Approach 1:
The patent extracts and removes the offset voltage component from the signal path by measuring it separately through a dedicated offset measurement circuit that connects to the Hall element outputs without the spinning current modulation. This separated offset measurement is then subtracted from the main measurement signal, effectively taking out the harmful offset component and allowing the front end amplifier and ADC to process only the relevant magnetic field signal with reduced dynamic range requirements.
Solution Approach 2:
The patent introduces an intermediary offset measurement circuit and processing stage that acts as a mediator between the Hall element and the front end amplifier. This intermediary circuit measures the offset voltage through resistive dividers and dedicated measurement paths, then compensates for it in the signal processing stage, thereby protecting the front end amplifier and ADC from the burden of processing large DC offset signals.
2Measurement precision
If spinning current technique is used to reduce offset voltage effects, then measurement precision is improved, but power consumption increases due to heavy burden on front end amplifier and ADC
Solution Approach 1:
The patent extracts and removes the offset voltage component from the signal path by measuring it separately through a dedicated offset measurement circuit that connects to the Hall element outputs without the spinning current modulation. This separated offset measurement is then subtracted from the main measurement signal, effectively taking out the harmful offset component and allowing the front end amplifier and ADC to process only the relevant magnetic field signal with reduced dynamic range requirements.
Solution Approach 2:
The patent changes the measurement parameters by using resistive dividers with specific resistance ratios to scale down the offset voltage to a measurable level. By adjusting the resistance values in the offset measurement circuit, the offset voltage is transformed into a smaller voltage range that can be measured and compensated without requiring the front end amplifier and ADC to handle large DC offset signals, thereby reducing power consumption.
3Measurement precision
If high dynamic range is designed in front end amplifier and ADC to accommodate large offset voltage, then measurement precision is improved, but cost increases
Solution Approach 1:
The patent extracts and removes the offset voltage component from the signal path by measuring it separately through a dedicated offset measurement circuit that connects to the Hall element outputs without the spinning current modulation. This separated offset measurement is then subtracted from the main measurement signal, effectively taking out the harmful offset component and allowing the front end amplifier and ADC to process only the relevant magnetic field signal with reduced dynamic range requirements.
Solution Approach 2:
The patent changes the measurement parameters by using resistive dividers with specific resistance ratios to scale down the offset voltage to a measurable level. By adjusting the resistance values in the offset measurement circuit, the offset voltage is transformed into a smaller voltage range that can be measured and compensated without requiring the front end amplifier and ADC to handle large DC offset signals, thereby reducing power consumption.
4Measurement precision
If high dynamic range is designed in front end amplifier and ADC to accommodate large offset voltage, then measurement precision is improved, but power consumption increases
Solution Approach 1:
The patent extracts and removes the offset voltage component from the signal path by measuring it separately through a dedicated offset measurement circuit that connects to the Hall element outputs without the spinning current modulation. This separated offset measurement is then subtracted from the main measurement signal, effectively taking out the harmful offset component and allowing the front end amplifier and ADC to process only the relevant magnetic field signal with reduced dynamic range requirements.
Solution Approach 2:
The patent changes the measurement parameters by using resistive dividers with specific resistance ratios to scale down the offset voltage to a measurable level. By adjusting the resistance values in the offset measurement circuit, the offset voltage is transformed into a smaller voltage range that can be measured and compensated without requiring the front end amplifier and ADC to handle large DC offset signals, thereby reducing power consumption.
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 effectively reduces the impact of offset voltage, minimizing the burden on circuitry and power consumption while maintaining accurate magnetic field detection, suitable for portable devices.
Implementation Method 1
Hall Effect sensors incorporate a Hall Effect plate, which is either an n- or p-doped area, supplied with bias current/voltage. In presence of a magnetic field the carriers that are moving in the doped area are deflected by the Lorentz force, and a Hall electrical field appears.
Implementation Method 2
In presence of a magnetic field the carriers that are moving in the doped area are deflected by the Lorentz force, and a Hall electrical field appears.
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
A Hall element sensor circuit in one embodiment includes a Hall element, a Hall element source, a switch matrix operatively connected to the Hall element and the Hall element source to establish a spinning current in the Hall element and to receive a Hall element signal from the Hall element based upon the spinning current, a front end amplifier including a first input operatively connected to a first switch matrix output and a second input operatively connected to a second switch matrix output, and at least one voltage source operatively connected to the front end amplifier at a location in the Hall element sensor circuit between the switch matrix and the front end amplifier.