Magnetic Sensor Circuit With Spinning-Current Offset Removal
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Solution Overview
Problem
Existing magnetic sensor circuits face challenges in suppressing changes in common-phase output voltage due to temperature and increasing current consumption, particularly when using operational amplifiers for high-speed switching to remove offset voltages.
Innovation Solution
A magnetic sensor circuit design that incorporates a Hall element, spinning circuit, modulation circuit, DC cut filter, amplifier circuit, demodulation circuit, and low pass filter, which together utilize the spinning current and chopping methods to remove offset voltages without increasing current consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If operational amplifiers are used for high-speed switching to remove offset voltages, then magnetic detection accuracy is improved, but current consumption increases
Solution Approach 1:
The patent applies periodic action by using a clock signal to periodically switch the polarity of the drive current flowing through the Hall element. This periodic polarity switching enables the spinning current method to remove offset voltages without requiring continuous high-speed operational amplifier switching, thereby reducing current consumption while maintaining magnetic detection accuracy.
Solution Approach 2:
The patent replaces the conventional operational amplifier-based high-speed switching mechanism with a simpler polarity switching circuit driven by a clock signal. This substitution eliminates the need for energy-intensive operational amplifiers while achieving the same offset voltage removal function through the spinning current method.
2Measurement precision
If offset voltages are removed using high-speed switching, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent uses periodic polarity switching driven by a clock signal to implement the spinning current method. This approach simplifies the circuit by replacing complex operational amplifier-based high-speed switching with a simpler periodic switching mechanism, reducing device complexity while maintaining measurement precision.
Solution Approach 2:
The patent substitutes complex operational amplifier circuits with a simpler polarity switching circuit that uses a clock signal. This replacement reduces the number of components and circuit complexity while achieving the same offset voltage removal function through the spinning current method.
3Stability of the object's composition
If temperature compensation is implemented, then stability of output voltage is improved, but current consumption increases
Solution Approach 1:
The patent applies periodic polarity switching to implement the spinning current method, which inherently compensates for temperature-induced offset voltage changes. This periodic switching mechanism provides temperature compensation without requiring additional active temperature compensation circuits that would increase current consumption.
Solution Approach 2:
The spinning current method provides self-service temperature compensation by utilizing the periodic polarity switching of the drive current itself. The method automatically compensates for temperature effects through the inherent properties of the Hall element and the switching mechanism, eliminating the need for separate temperature compensation circuits and reducing current 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 design effectively suppresses temperature-induced changes in common-phase output voltage and enhances magnetic detection accuracy by removing offset voltages using the spinning current and chopping methods, while maintaining low current consumption.
Implementation Method 1
A Hall element utilizes the Hall effect and is a magnetoelectric conversion element that outputs a differential voltage proportional to the strength of the applied magnetic field
Data Source
AI summary
A magnetic sensor circuit 100 includes: a Hall element 111, outputting a Hall voltage VH and an offset voltage VHos; a switch unit 120, setting the Hall voltage VH as an AC component and the offset voltage VHos as a DC component; a first DC cut filter 130, allowing the Hall voltage VH of the AC component to pass through and cutting off the offset voltage VHos of the DC component, and setting, to a predetermined common-phase voltage V3C, a common-phase voltage V2C; an amplifier circuit, amplifying a voltage in which an offset voltage VAMPos to the Hall voltage; a demodulation circuit, demodulating the Hall voltage VH of the AC component and modulating the offset voltage VAMPos of the DC component; and a low pass filter 160, allowing the Hall voltage VH of the DC component and cutting off the offset voltage VAMPos of the AC component.