Hall-effect sensor offset cancellation via four-phase spinning
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Solution Overview
Problem
Hall-effect sensors face measurement errors due to offset effects, particularly a transient offset phenomenon caused by dielectric polarization, which affects the accuracy of magnetic field measurements.
Innovation Solution
A new four-phase spinning scheme is introduced, where the source and ground terminals are interchanged between measurement phases, and the terminals used for measurement are reassigned as source and ground, substantially canceling the transient offset by averaging the measured Hall voltages across different terminal orientations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional Hall-effect sensor measurement is used, then the device structure is simple, but measurement precision deteriorates due to offset voltage effects
Solution Approach 1:
The patent applies periodic action by implementing a four-phase spinning measurement scheme where the current direction is periodically reversed between opposite terminals. This periodic reversal of current direction allows the transient offset voltage to be canceled out through averaging, thereby improving measurement precision without requiring additional hardware components.
Solution Approach 2:
The patent utilizes parameter changes by dynamically switching the polarity of the source voltage applied across the Hall-effect sensor terminals. By changing the voltage polarity between measurement phases and averaging the results, the transient offset is eliminated while maintaining the same physical device structure, thus improving accuracy without increasing device complexity.
2Measurement precision
If four-phase spinning scheme is implemented, then measurement precision improves by canceling transient offset, but device complexity increases due to additional control circuitry
Solution Approach 1:
The control circuit implements multi-functionality by using the same measurement circuitry to perform both standard Hall voltage measurement and transient offset cancellation through the four-phase spinning scheme. The existing voltage sources and measurement channels are utilized in multiple configurations, eliminating the need for separate dedicated circuits for offset cancellation.
Solution Approach 2:
The measurement system performs self-service by using its own internal voltage sources and measurement channels to automatically cancel the transient offset. The control circuit reuses the existing Hall sensor terminals and measurement infrastructure, allowing the system to compensate for its own errors without requiring external calibration equipment or additional specialized components.
3Measurement precision
If current direction is reversed between terminals, then transient offset is canceled, but measurement time increases due to multiple measurement phases
Solution Approach 1:
The patent maintains continuity of useful action by performing all four measurement phases in rapid succession without idle periods between them. The current direction is continuously reversed through the four phases, and all measurements are taken in an uninterrupted sequence, allowing the offset cancellation to be achieved with minimal additional time overhead.
Solution Approach 2:
The measurement system performs preliminary action by pre-establishing the four-phase measurement sequence and preparing the voltage switching circuitry before actual measurement begins. This allows the rapid execution of the four-phase spinning scheme, minimizing the overall time penalty by eliminating setup and transition delays.
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 approach significantly reduces measurement errors by canceling out transient offset voltages, leading to more accurate detection of magnetic fields compared to conventional methods.
Implementation Method 1
Hall-effect sensors may be implemented as dedicated devices or integrated with other circuitry to provide measurement of magnetic fields
Implementation Method 2
a transient offset phenomenon caused by dielectric polarization
Data Source
AI summary
A semiconductor device includes first and second Hall-effect sensors. Each sensor has first and third opposite terminals and second and fourth opposite terminals. A control circuit is configured to direct a current through the first and second sensors and to measure a corresponding Hall voltage of the first and second sensors. Directing includes applying a first source voltage in a first direction between the first and third terminals of the first sensor and applying a second source voltage in a second direction between the first and third terminals of the second sensor. A third source voltage is applied in a third direction between the second and fourth terminals of the first sensor, and a fourth source voltage is applied in a fourth direction between the second and fourth terminals of the second sensor. The third direction is rotated clockwise from the first direction and the fourth direction rotated counter-clockwise from the second direction.