Hall Sensor Temperature Compensation Circuit
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Solution Overview
Problem
Existing methods for temperature compensation in Hall sensors are limited by their reliance on approximate linear models, are not compatible with low-noise applications due to non-linear temperature dependencies, and result in extra current consumption and sensitivity to process variations, especially at large bias currents.
Innovation Solution
A variable gain compensation circuit using a Hall-type element in a feedback loop to simulate resistance behavior, adjusting the resistance of a compensation element formed in the same epitaxial layer as the Hall sensor to track sensitivity drift and compensate for temperature dependence, independent of bias voltage and process corners.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a shunt resistor is used to redistribute supply current for temperature compensation, then Hall sensor sensitivity drift can be compensated, but extra current consumption is introduced and the system becomes sensitive to process variations
Solution Approach 1:
The invention extracts the compensation function from a separate shunt resistor circuit and integrates it into the Hall sensor element itself. By forming the compensation element directly in the same epitaxial layer as the Hall sensor, the patent eliminates the need for external current redistribution circuits, thereby removing the extra current consumption while maintaining temperature compensation capability.
Solution Approach 2:
The patent merges the Hall sensor element and the compensation element into a single integrated structure formed in the same epitaxial layer. This combination allows both the sensing function and the temperature compensation function to be performed by the same physical structure, eliminating the need for separate compensation circuits and reducing overall current consumption.
2Reliability
If a shunt resistor is used for temperature compensation, then sensitivity drift can be tracked, but the system becomes sensitive to process variations with compensation resistor unable to properly track Hall sensor parameters
Solution Approach 1:
The invention applies local quality by forming both the Hall sensor element and the compensation element in the same epitaxial layer with identical local material properties and fabrication conditions. This ensures that both elements experience the same process variations, allowing the compensation element to accurately track the Hall sensor parameters despite manufacturing variations.
Solution Approach 2:
The patent uses homogeneity by ensuring that the Hall sensor element and compensation element are formed in the same epitaxial layer with uniform material composition and structure. This homogeneous formation process guarantees that both elements respond identically to process variations, enabling accurate parameter tracking without sensitivity to manufacturing deviations.
3Ease of manufacture
If linear temperature behavior model is used for Hall sensor sensitivity, then compensation can be implemented, but the model only represents an approximate behavior and is not accurate for large bias currents
Solution Approach 1:
The invention applies dynamics by making the compensation element's resistance variable with temperature through bias voltage control, rather than using a fixed linear compensation model. The depletion region thickness in the compensation element can be dynamically adjusted via the P-well voltage to match the non-linear temperature dependence of the Hall sensor, enabling accurate compensation across large temperature ranges and bias currents.
Solution Approach 2:
The patent uses parameter changes by varying the depletion region thickness of the compensation element through controlled bias voltage applied to the P-well. This dynamic parameter adjustment allows the compensation element's resistance to track the non-linear temperature behavior of the Hall sensor sensitivity, providing accurate compensation beyond the limitations of linear models.
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 provides high temperature stability and accuracy, effectively compensating residual temperature dependence and amplifying Hall signals while tracking sensitivity drift without requiring process corner calibration.
Implementation Method 1
A variable gain compensation circuit using a Hall-type element in a feedback loop to simulate resistance behavior
Implementation Method 2
a change may be provided in the depletion region in the N-well causing a change of the equivalent thickness t which affects the Hall plate resistance value
Data Source
AI summary
A compensation circuit receives a sensing signal from a Hall sensor and outputs a compensated Hall sensing signal. The compensation circuit has a gain that is inversely proportional to Hall sensor drift mobility. The compensated Hall sensing signal is temperature-compensated.