CVH Sensor Angle Detection via Sliding Window Integration
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Solution Overview
Problem
Existing magnetic field sensors using circular vertical Hall (CVH) sensing elements face challenges in accurately determining the angle of a magnetic field due to offset errors and inefficiencies in signal processing, particularly in processing quadrature modulated signals from multiple vertical Hall elements.
Innovation Solution
The solution involves a processor stage that performs sliding window integration and quadrature modulation of signals from multiple vertical Hall elements, using a sigma-delta analog-to-digital converter to shift noise to higher frequencies, and calculates the estimated angle through arctangent functions, enabling precise angle determination beyond the frequency of the CVH cycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional signal processing methods are used for CVH sensing elements, then the device complexity is lower, but the measurement precision of magnetic field angle is insufficient due to offset errors
Solution Approach 1:
The patent applies preliminary action by performing sliding window integration on quadrature modulated signals before angle calculation. The integration process pre-processes the signals to reduce offset errors and improve measurement precision, calculating integrated values over sliding windows that overlap by half a cycle. This preliminary integration step eliminates the need for complex post-processing corrections.
Solution Approach 2:
The patent introduces quadrature modulation as an intermediary process between signal acquisition and angle calculation. By modulating the CVH sensing element signals with quadrature carriers and then integrating these modulated signals, the system creates an intermediate representation that simplifies subsequent angle extraction while improving precision through the modulation-integration process.
2Measurement precision
If sliding window integration with overlapping portions is used, then the measurement precision improves through noise filtering, but the processing time increases
Solution Approach 1:
The patent implements continuity of useful action through overlapping sliding windows where each subsequent window starts before the previous one completes. The windows overlap by half a cycle, allowing continuous processing without gaps. This approach maintains high measurement precision through adequate sampling while reducing overall processing time compared to sequential non-overlapping windows.
Solution Approach 2:
The patent applies partial action by integrating over sliding windows that cover only portions of the full signal cycle rather than requiring complete cycle integration. The overlapping windows provide sufficient integration for noise filtering while avoiding the time penalty of waiting for full cycles to complete, achieving a balance between precision and speed.
3Measurement precision
If quadrature modulation is applied to CVH signals, then the measurement precision of angle determination improves, but the device complexity increases due to additional processing circuits
Solution Approach 1:
The patent applies universality by designing the processor stage to perform multiple functions: quadrature modulation, sliding window integration, and angle calculation all within a single integrated processing unit. This multi-functional approach improves angle resolution through quadrature techniques while minimizing the increase in device complexity by consolidating processing functions rather than adding separate dedicated circuits for each operation.
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 enhances the accuracy and resolution of magnetic field angle detection by averaging integrations and filtering noise, providing a more precise output signal with reduced offset errors and increased throughput.
Implementation Method 1
One type of current sensor uses a Hall effect magnetic field sensing element in proximity to a current-carrying conductor.
Implementation Method 2
The analog-to-digital converter may be a sigma-delta analog-to-digital converter comprising a noise shaping transform that shifts quantization noise to higher frequencies
Data Source
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AI summary
A magnetic field sensor comprises a circular vertical Hall (CVH) sensing element comprising a plurality of vertical Hall elements, each vertical Hall element comprised of a respective group of vertical Hall element contacts selected from among a plurality of vertical Hall element contacts. A quadrature modulator circuit is coupled to the digital signal and operable to generate a plurality of quadrature modulated signals. A processor stage is coupled to receive the signals representative of the plurality of quadrature modulated signals, and operable to perform a sliding window integration using the signals representative of the plurality of quadrature modulated signals and compute an estimated angle of the external magnetic field using the signals representative of the plurality of quadrature modulated signals.