MEMS Accelerometer Equalization for Flat Wideband Frequency Response
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
MEMS accelerometers have limited measurement bandwidth and noise issues due to resonant behavior, which restricts the flatness of frequency response and increases noise at higher frequencies, making it challenging to extend the usable frequency range without increasing noise.
Innovation Solution
A digital equalization filter is applied to digitized acceleration signals from MEMS accelerometers, using the transfer function to flatten the frequency response and extend the measurement bandwidth beyond the resonant frequency, while also incorporating temperature compensation to reduce noise and maintain accuracy across a broad frequency range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the resonant frequency f0 of the MEMs sensor is increased to extend measurement bandwidth, then the measurement bandwidth is widened, but noise increases because noise is proportional to the square of f0
Solution Approach 1:
The patent replaces mechanical optimization (changing f0) with digital signal processing (digital equalization filter) to extend bandwidth. Instead of physically adjusting the sensor's resonant frequency, the system uses digital filtering to flatten the frequency response in software, thereby extending usable bandwidth without increasing noise.
Solution Approach 2:
The patent changes the frequency response characteristics through digital parameter adjustment rather than physical parameter change. By applying digital equalization with specific filter coefficients, the system modifies the frequency response curve to achieve extended bandwidth while maintaining low noise levels.
2Object-affected harmful factors
If the resonant frequency f0 is kept low to reduce noise, then noise is reduced, but the frequency response peaks rapidly beyond the measurement band, limiting usable bandwidth
Solution Approach 1:
The patent substitutes mechanical frequency response characteristics with digitally programmed frequency response. Instead of relying on the physical resonant behavior of the MEMs sensor, the system uses a digital equalization filter to create a flattened frequency response that extends beyond the natural bandwidth limits.
Solution Approach 2:
The patent converts the harmful resonant peaking effect into a beneficial extended bandwidth. By digitally equalizing the frequency response, the system takes the natural resonant behavior and transforms it into an extended usable frequency range through inverse filtering.
3Speed
If a digital equalization filter is applied to extend bandwidth beyond resonant frequency, then measurement bandwidth is extended, but device complexity increases due to additional processing circuitry
Solution Approach 1:
The patent makes the existing processing circuitry multi-functional by having it perform both standard signal processing and digital equalization functions. The same processor that handles basic sensor data also implements the equalization filter, eliminating the need for separate dedicated hardware and reducing overall device complexity.
Solution Approach 2:
The patent merges the equalization filter functionality with the existing signal processing pipeline. By integrating the digital equalization into the existing processing architecture rather than adding separate hardware, the system extends bandwidth while minimizing increases in device complexity.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Sensor apparatus and methods for operating the same for measuring acceleration are disclosed. In some embodiments, circuitry inside a sensor digitizes a measured acceleration signal from an accelerometer into a digitized acceleration signal, which is processed by a digital equalization filter within the sensor to provide an equalized acceleration signal. The equalized acceleration signal may have a frequency response that is substantially flat over a frequency range that extends beyond the resonant frequency of a MEMs sensor within the accelerometer of the sensor.