Round-Robin Sensor Circuit for Low-Alias Multi-Axis Readout
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Solution Overview
Problem
Existing multi-channel sensor systems face challenges with noise aliasing and unwanted harmonics, leading to increased current consumption and circuit area, particularly when processing multiple axes simultaneously, as they require separate circuits and amplifiers for each axis, resulting in inefficiencies and noise penalties.
Innovation Solution
A round robin sensor device is introduced, utilizing a multiplexer stage, a resettable charge-to-voltage converter, and a Nyquist analog-to-digital converter, which sequentially selects and processes sensor outputs from multiple axes, reducing noise aliasing and eliminating unwanted harmonics by resetting the integrator and converter between sampling periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate circuits and amplifiers are used for each sensor axis, then measurement precision is maintained, but device complexity and current consumption increase
Solution Approach 1:
The patent combines multiple sensor axis processing into a single shared circuit architecture. A multiplexer sequentially switches between different sensor axes, allowing one charge-to-voltage converter and one analog-to-digital converter to service multiple sensors. This merging approach maintains measurement precision through dedicated processing paths while dramatically reducing device complexity by eliminating the need for separate amplifier circuits for each axis.
Solution Approach 2:
The charge-to-voltage converter and analog-to-digital converter are designed as universal components that can process signals from any sensor axis. The multiplexer enables these components to be reused across multiple sensing channels in a time-division manner, making the circuit architecture multi-functional rather than dedicated to a single axis.
2Measurement precision
If separate amplifiers are used for each sensor axis, then signal processing quality is maintained, but current consumption increases
Solution Approach 1:
Multiple amplifier functions are merged into a single charge-to-voltage converter that is time-shared across different sensor axes. The converter processes signals from one axis at a time through the multiplexer, eliminating the need for multiple simultaneous amplifier operations and thus reducing total current consumption while maintaining signal processing quality for each axis.
Solution Approach 2:
The system employs periodic action through the multiplexer, which sequentially switches between different sensor axes at regular intervals. This time-division multiplexing allows a single amplifier to serve multiple axes periodically, reducing the overall power requirement compared to having all amplifiers operating simultaneously, while ensuring each axis receives dedicated processing attention.
3Productivity
If continuous sensing of all sensor outputs is performed, then productivity is improved, but noise aliasing and unwanted harmonics increase
Solution Approach 1:
The multiplexer implements periodic action by sequentially selecting and processing sensor outputs in a systematic time-division manner. This periodic switching allows continuous sensing throughput across all axes while introducing regular, predictable sampling patterns that facilitate proper anti-aliasing filtering and reduce random noise accumulation compared to truly simultaneous processing of all channels.
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 minimizes current consumption and circuit area while improving noise performance by continuously rotating through sensor axes with a single set of circuits, reducing noise aliasing and harmonic penalties, and allowing for efficient signal gain and data processing.
Implementation Method 1
Each pair of capacitive plates is part of a respective sensing channel associated with a respective axis. When tilt or acceleration is applied to the MEMS sensor, the movement in suspended mass creates capacitance change.
Implementation Method 2
a resettable integrator operatively coupled to the charge-to-voltage converter and configured to demodulate and integrate the voltage, resulting in an integrated voltage
Data Source
AI summary
A round robin sensor device for processing sensor data is provided herein. The sensor device includes a multiplexer stage configured to sequentially select sensor outputs from one or more sensors continuously. Continuously and sequentially selecting sensor outputs results in a stream of selected sensor outputs. The sensor device also includes a charge-to-voltage converter operatively coupled to the multiplexer stage and configured to convert a charge from a first sensor of the one or more sensors to a voltage. Further, the sensor device includes a resettable integrator operatively coupled to the charge-to-voltage converter and configured to demodulate and integrate the voltage, resulting in an integrated voltage. Also included in the sensor device is an analog-to-digital converter operatively coupled to the resettable integrator and configured to digitize the integrated voltage to a digital code.