MEMS ASIC Overload Recovery via Dynamic High-Ohmic Impedance
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Solution Overview
Problem
Microelectromechanical system (MEMS) sensors integrated with application-specific integrated circuits (ASICs) face challenges in recovering from overload events, leading to extended settling times and inaccurate signal sampling due to changes in DC operating levels, which affects the quality of information sampled during such events.
Innovation Solution
Incorporating an overload detector within the MEMS ASIC that adjusts the impedance of high-ohmic blocks to reduce the settling time by changing the resistance of adjustable HO blocks, such as those including resistors and MOSFETs, to quickly restore the DC operating level and cutoff frequency of the high-pass filter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the MEMS ASIC operates at its targeted DC operating level, then accurate signal sampling is achieved, but during an overload event the DC operating level changes and settling time increases
Solution Approach 1:
The patent implements dynamic adjustment of the high-ohmic block impedance based on overload detection. The system transitions from a static impedance design to a dynamic one that adapts to operating conditions. When an overload event is detected, the impedance is adjusted to accelerate settling, and when normal operation is detected, the impedance returns to its original value to maintain filtering performance.
Solution Approach 2:
The patent changes the impedance parameter of the high-ohmic block dynamically. By adjusting the resistance value of the high-ohmic block based on overload conditions, the system optimizes the settling time constant. The impedance parameter is modified from a fixed value to a variable value that responds to system state, directly addressing the settling time issue.
2Stability of the object's composition
If the high-ohmic block maintains a fixed impedance, then the high-pass filter cutoff frequency remains stable, but the settling time after overload event is extended
Solution Approach 1:
The system transitions from a static high-pass filter design to a dynamic one. The high-ohmic block impedance is made adjustable, allowing the filter characteristics to change dynamically based on operating conditions. This enables the system to optimize settling behavior during overload events while maintaining stable filtering during normal operation.
Solution Approach 2:
The overload detector continuously monitors the system state and prepares to adjust the high-ohmic block impedance before significant settling issues occur. By detecting overload conditions early and proactively adjusting the impedance, the system minimizes the settling time without waiting for the DC operating level to drift significantly.
3Speed
If the impedance of the high-ohmic block is adjusted to reduce settling time, then recovery speed improves, but the high-pass filter cutoff frequency may change
Solution Approach 1:
The system uses periodic monitoring of the DC operating level by the overload detector to determine when to adjust and when to restore the high-ohmic block impedance. This periodic check ensures that impedance changes are made at appropriate times - during overload for fast recovery, and after recovery to restore filtering - rather than continuously, maintaining stability when not needed.
Solution Approach 2:
The overload detector provides feedback about the DC operating level to the high-ohmic block control mechanism. This feedback loop enables the system to automatically adjust the impedance when overload is detected and restore it when normal operation returns, creating a self-regulating system that balances recovery speed and filter stability based on real-time conditions.
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 solution enables the MEMS ASIC to recover faster from overload events, allowing for accurate signal sampling sooner and reducing the impact of overload events on the quality of sampled information, thereby improving the operational reliability of MEMS sensors in compact electronic devices.
Implementation Method 1
The HO block and the MEMS can form a high-pass filter (HPF). The impedance of the HO block can be related to the DC operating level of the AFE amplifier and the cutoff frequency of the HPF.
Implementation Method 2
adjusts the impedance of high-ohmic blocks to reduce the settling time by changing the resistance of adjustable HO blocks, such as those including resistors and MOSFETs
Data Source
AI summary
Disclosed herein is a MEMS ASIC. In some examples, the MEMS ASIC can include a MEMS, an analog front end (AFE) amplifier, an analog-to-digital converter (ADC), an overload detector, and a high-ohmic (HO) block. The HO block and the MEMS can form a high-pass filter (HPF). The impedance of the HO block can be related to the DC operating level of the AFE amplifier and the cutoff frequency of the HPF. In some examples, an overload event can occur, and the overload detector can be configured to adjust the impedance of the HO block to reduce the settling time of the MEMS ASIC. Methods of using the MEMS ASIC to reduce the settling time of the MEMS ASIC due to an overload event are disclosed herein.