Chopper-Stabilized Amplifier for Fast, Accurate Hall Sensors
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Solution Overview
Problem
Conventional chopper-stabilized amplifiers and magnetic field sensors face limitations in supporting high switching frequencies, resulting in slow response times and low rejection of common mode and offset components, which affects the accuracy of magnetic field sensing.
Innovation Solution
A chopper-stabilized amplifier design with first and second front-end amplifiers, a switching network, and back-end amplifiers, coupled with a modulation circuit and filter, to modulate and demodulate magnetic field signals while rejecting offset components, enabling high switching frequencies and improved common mode rejection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional chopper-stabilized amplifiers are used, then offset component reduction is achieved, but switching frequency is limited resulting in slow response time
Solution Approach 1:
The amplifier is divided into multiple stages: a first chopper-stabilized amplifier stage that processes the signal at a first switching frequency, and a second chopper-stabilized amplifier stage that processes the signal at a second switching frequency. This segmentation allows each stage to operate at optimized frequencies, achieving both high offset rejection and fast response time by combining the outputs of both stages.
2Measurement precision
If conventional chopper-stabilized amplifiers are used, then offset component reduction is achieved, but common mode rejection is low
Solution Approach 1:
Each chopper-stabilized amplifier stage is designed with specific local characteristics optimized for its function. The first stage uses particular compensation components and switching configurations optimized for its frequency range, while the second stage uses different configurations optimized for its frequency range. This local optimization of each stage's quality characteristics enables both high offset rejection and high common mode rejection when the stages are combined.
3Speed
If switching frequency is increased to improve response time, then response time improves, but offset component rejection and common mode rejection deteriorate
Solution Approach 1:
The system employs periodic switching at two different frequencies. The first chopper-stabilized amplifier switches at a first periodic frequency while the second switches at a second periodic frequency. This multi-frequency periodic action allows the system to achieve fast response characteristics from the higher frequency stage while maintaining offset and common mode rejection through the coordinated operation of both stages, with each stage being optimized for its specific frequency range.
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 solution allows for faster response times and higher rejection of offset and common mode signals, enhancing the accuracy and efficiency of magnetic field sensors.
Implementation Method 1
Some types of magnetic field sensors use a Hall effect element, sometimes referred to as a Hall plate. A Hall effect element can generate a signal with both a signal component and an offset component
Data Source
AI summary
A chopper-stabilized amplifier has switching networks arranged to support a high frequency clocking signal and to provide a high common mode rejection and a high rejection of an offset component of an input signal. A magnetic field sensor includes a Hall effect element coupled to a modulation circuit. The modulation circuit provides a signal to the chopper-stabilized amplifier. The chopper-stabilized amplifier provides an output signal to a low pass filter, which provides an output signal from the magnetic field sensor.