Multichannel Magnetic Sensor Signal Path for Speed and Area Balance
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Solution Overview
Problem
Magnetic field sensors with multiple channels face challenges in achieving high operating speed and reducing circuit area while minimizing DC offset voltage, particularly in applications requiring efficient processing of magnetic field signals from multiple sensing elements.
Innovation Solution
A multichannel magnetic field sensor design featuring a multiplexed signal path with shared front-end amplifiers and Schmitt trigger circuits, separate low-pass filters, and sinc filter sampling capacitors for each channel, allowing for efficient processing and demodulation of magnetic field signals while minimizing circuit redundancy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a fully shared signal path is used for multiple channels, then circuit area is reduced and cost is lowered, but operating speed decreases due to signal multiplexing delays
Solution Approach 1:
The patent segments the signal path into shared components (front-end amplifier, Schmitt trigger circuit) and dedicated components (low-pass filter, sinc filter sampling capacitor) for each channel. This segmentation allows each channel to have its own filtering resources while sharing amplification and triggering resources, thereby maintaining high operating speed while reducing circuit area compared to fully separate paths.
2Speed
If fully separate redundant signal paths are used for each channel, then operating speed is maintained, but circuit area increases and cost increases
Solution Approach 1:
The patent merges the front-end amplifier and Schmitt trigger circuit into shared resources that serve multiple channels through time-division multiplexing. The amplifier processes signals from different channels at different time intervals, and the Schmitt trigger circuit similarly shares processing between channels. This merging reduces the total circuit area while maintaining operating speed through the dedicated filter paths for each channel.
3Device complexity
If DC offset voltage is not compensated, then circuit complexity is reduced, but measurement precision deteriorates due to undesirable DC offset voltage in Hall Effect elements
Solution Approach 1:
The patent implements periodic action through the Schmitt trigger circuit that operates in conjunction with the shared front-end amplifier. The trigger circuit periodically processes signals from different channels at different time intervals, enabling DC offset compensation through the time-division multiplexing approach. This periodic processing maintains measurement precision while keeping the overall circuit complexity manageable through resource sharing.
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 design enhances operating speed, reduces circuit area, and lowers costs compared to fully shared or fully separate signal paths, effectively addressing the challenges of DC offset voltage and signal processing efficiency in magnetic field sensors.
Implementation Method 1
a magnetic field sensing element, such as a Hall effect element or a magnetoresistive element, to sense a magnetic field
Data Source
AI summary
A multichannel magnetic field sensor including a plurality of magnetic field sensing elements includes a multiplexed signal path. A front end amplifier is coupled to receive a first magnetic field signal during a first time interval and a second magnetic field signal during a second time interval. A first low pass filter processes the amplified signal during the first time interval and a second low pass filter processes the amplified signal during the second time interval. A sinc filter is coupled to receive the first low pass filtered signal during the first time interval and the second low pass filtered signal during the second time interval. A Schmitt trigger circuit includes a comparator to process the sinc filter output signal and to generate a first comparator output signal during the first time interval and a second comparator output signal is provided during the second time interval.