Oscillator Characterization Using Sinc-Pulse Spectral Measurement
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Solution Overview
Problem
Current methods for determining the resonance frequency and quality factor of electrostatically actuated oscillators in MEMS or NEMS are either time-consuming, requiring oscillators to return to rest position, or suffer from parasitic capacitance issues that obscure measurement signals, limiting productivity and accuracy.
Innovation Solution
A method involving a combined sinusoidal voltage and voltage pulse excitation, where the voltage pulse is shaped as a cardinal sine function, allowing for rapid acquisition of response signals in the time domain and transformation into frequency domain to determine characteristic parameters without needing oscillators to return to rest, and suppressing parasitic signal interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If frequency scanning measurement method is used to accurately measure resonant frequency and quality factor, then measurement precision is improved, but measurement time increases significantly
Solution Approach 1:
The patent applies periodic action by using a voltage pulse with periodic cardinal sine function characteristics to excite the oscillator. This periodic excitation pattern allows the system to obtain complete spectral density information in a single measurement cycle, eliminating the need for repeated frequency scanning while maintaining measurement accuracy for resonant frequency and quality factor determination.
Solution Approach 2:
The patent changes the excitation parameter from continuous frequency sweeping to a fixed-frequency voltage pulse with specific temporal characteristics (cardinal sine function). This parameter change transforms the measurement approach from time-consuming frequency domain scanning to a single time-domain excitation followed by spectral analysis, significantly reducing measurement time while preserving precision.
2Productivity
If voltage pulse excitation is used to reduce measurement time, then productivity is improved, but parasitic capacitance interference increases
Solution Approach 1:
The patent converts the harmful parasitic capacitance effect into a beneficial signal characteristic. By using voltage pulse excitation with cardinal sine function, the parasitic capacitance generates a predictable spectral pattern that can be identified and separated from the true oscillator response. The harmful interference is transformed into a known artifact that aids in signal validation and processing.
Solution Approach 2:
The patent introduces spectral density analysis as an intermediary processing step between excitation and measurement. This intermediary transformation converts the time-domain signal (containing both useful oscillator response and parasitic capacitance interference) into frequency-domain spectral density, where the parasitic signals and true oscillator signals appear at different frequencies and can be selectively analyzed.
3Measurement precision
If oscillator must return to resting position between measurements, then measurement accuracy is improved, but measurement speed decreases
Solution Approach 1:
The patent applies preliminary action by using a voltage pulse excitation that naturally decays after a predetermined duration. The excitation pulse is designed to provide sufficient energy to the oscillator to achieve maximum amplitude response, and the pulse duration is carefully selected to allow complete energy dissipation before the next measurement, eliminating the need for additional waiting time while ensuring accurate amplitude measurements.
Solution Approach 2:
The patent maintains continuity of useful action by overlapping the measurement acquisition window with the oscillator's natural decay period. Instead of idle waiting time between measurements, the system continuously acquires data during the oscillator's natural response decay, maximizing the utilization of measurement time and increasing productivity without sacrificing accuracy.
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
Enables rapid and reliable characterization of oscillators by obtaining complete spectral density in seconds, with constant amplitude spectral density of the electrostatic actuation force, reducing measurement time and enhancing accuracy by minimizing parasitic signal impact.
Implementation Method 1
actuation means that transform an excitation signal applied to the oscillator's input into an electrostatic actuation force
Implementation Method 2
The displacements of the moving element are measured by sensing means that generate a response signal at the oscillator's output
Implementation Method 3
The oscillations of the moving element are governed by equations of motion... the resonant frequency is then also modified
Data Source
Figure 1~2B
Figure 3~5
Figure 6~8
AI summary
The present invention relates to a method for determining characteristic parameters of an electrostatically actuated oscillator, the method comprising the following steps: - generating a first excitation voltage defined as the sum of a first sinusoidal voltage and a voltage pulse; - applying the first excitation voltage to the input of the oscillator; - acquiring in the time domain a first response voltage present at the output of the oscillator when the first excitation voltage is applied to the input of the oscillator; - obtaining, by transformation in the frequency domain, a first spectral density of amplitude (500) of the first response voltage; - determining the characteristic parameters of the oscillator from the first spectral density of amplitude (500).