Hall Sensor with Orthogonal Channels for High Bandwidth Sensing
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Solution Overview
Problem
High-speed Hall sensors face limitations due to capacitive load and circuit complexity, particularly in applications requiring high bandwidth and lossless current sensing, such as in the automotive sector.
Innovation Solution
A Hall sensor system with an octagonal sensing element and separated contacts, utilizing a 'spinning' current scheme to reduce offset, featuring two orthogonal sensing channels for compressive data sensing and auto-zeroing of op-amp offset, allowing for high bandwidth up to 1 MHz and rejection of earth magnetic fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a conventional Hall sensor with single feedback loop and ADC/DAC conversion is used, then the circuit complexity is reduced, but the bandwidth is limited and offset-induced ripples occur
Solution Approach 1:
The patent segments the sensing function into two orthogonal channels (X and Y directions), each with independent bias electrodes and sensing electrodes. This segmentation allows simultaneous measurement in multiple directions without requiring complex sequential switching, achieving high bandwidth while maintaining manageable circuit complexity through modular architecture
Solution Approach 2:
The patent implements periodic action through the spinning current scheme that alternates bias current direction between positive and negative phases. This periodic reversal enables dynamic offset cancellation by measuring Hall voltage in both current directions and computing the difference, eliminating offset-induced ripples while maintaining high-speed operation up to 1 MHz
2Measurement precision
If a spinning current scheme is implemented to reduce offset, then offset-induced ripples are reduced, but the capacitive load of switches increases
Solution Approach 1:
The patent employs feedback through differential measurement where the Hall voltage is measured during both positive and negative bias current phases, and the offset is cancelled by computing V_H = (V_H+ - V_H-)/2. This feedback mechanism dynamically eliminates offset errors without requiring large switch capacitances, reducing the capacitive load penalty while maintaining high measurement precision
Solution Approach 2:
The patent changes the parameter of bias current direction periodically, switching between positive and negative phases. This parameter change enables offset cancellation through differential measurement while using small-capacitance switches, as the spinning scheme requires minimal charge transfer compared to traditional large-capacitance switching approaches
3Measurement precision
If two orthogonal sensing channels are used for compressive sensing, then measurement precision is improved, but the device complexity increases
Solution Approach 1:
The patent implements multi-functionality by using two orthogonal sensing channels that can simultaneously measure magnetic field components in X and Y directions. Each channel serves dual purposes: individual directional sensing and collaborative offset cancellation, achieving enhanced measurement precision without proportionally increasing device complexity through efficient resource utilization
Solution Approach 2:
The patent merges the offset cancellation function with the dual-channel sensing function. The same two orthogonal channels used for directional measurement also perform offset cancellation through differential measurement, combining multiple functions into a unified structure that reduces overall device complexity compared to separate offset cancellation circuits
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
Enables high bandwidth lossless current sensing, reduces offset-induced ripples, and dynamically adjusts acquisition bandwidth based on an external clock frequency, effectively addressing the limitations of existing Hall sensors.
Implementation Method 1
a Hall sensing element configured to produce a Hall voltage indicative of a magnetic field when traversed by an electric current
Data Source
AI summary
A Hall sensor may include a Hall sensing element configured to produce a Hall voltage indicative of a magnetic field when traversed by an electric current, and a first pair of bias electrodes mutually opposed in a first direction across the Hall sensing element. The Hall sensor may include a second pair of bias electrodes mutually opposed in a second direction across the Hall sensing element. The Hall sensor may include a first pair of sensing electrodes mutually opposed in a third direction across the Hall sensing element, and a second pair of sensing electrodes mutually opposed in a fourth direction across the Hall sensing element. The fourth direction may be orthogonal to the third direction, each sensing electrode being between a bias electrode of the first pair and a bias electrode of the second pair.