MEMS Voltmeter Teeter-Totter Proof Mass for High-Frequency RMS Measurement
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Solution Overview
Problem
Current Root Mean Square (RMS) voltmeters have limited bandwidth, are complex, expensive, and suffer from non-ideal diode behavior, making them ineffective for accurately measuring AC voltages and high-frequency signals.
Innovation Solution
The development of a Microelectromechanical Systems (MEMS) voltmeter using a teeter-totter structured proof mass and a rebalancing circuit that generates a drive voltage based on the position of the proof mass to calculate the RMS value of an input voltage, overcoming non-ideal diode behavior with electrostatic forces and achieving high-frequency response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If semiconductor diode networks are used to form an approximation of the absolute value of the incoming voltage, then the voltmeter can measure AC voltages and complex waveforms, but the measurement accuracy deteriorates due to non-zero voltage at which semiconductor diodes switch
Solution Approach 1:
The patent replaces semiconductor diode networks with a mechanical MEMS system consisting of a proof mass, sense plates, and drive plates. The electrostatic forces acting on the proof mass provide a purely mechanical means of detecting voltage magnitude without the nonlinear switching characteristics of semiconductor diodes, thereby resolving the contradiction between versatility and measurement precision.
2Measurement precision
If conventional RMS voltmeter designs are used, then AC voltage measurements can be performed, but the bandwidth is limited and the device becomes complex, expensive, and large
Solution Approach 1:
The patent segments the voltmeter into distinct functional components: a proof mass for force sensing, sense plates for detecting proof mass position, and drive plates for applying electrostatic forces. This segmentation allows each component to be optimized independently and integrated into a compact MEMS structure, reducing overall device complexity while maintaining RMS measurement capability.
Solution Approach 2:
The patent transitions from conventional electrical circuit implementations to a three-dimensional MEMS structure where the proof mass can deflect in multiple directions and the electrostatic fields interact in three-dimensional space. This dimensional transition enables more efficient use of space and reduces device footprint while improving bandwidth.
3Measurement precision
If conventional voltmeter designs are used, then voltage measurements can be performed, but the bandwidth is limited and high-frequency signal measurement becomes ineffective
Solution Approach 1:
The patent changes the fundamental operating parameters of the voltmeter by using electrostatic forces with purely quadratic voltage dependence rather than semiconductor switching characteristics. This parameter change eliminates bandwidth limitations imposed by diode switching times and allows the system to respond to high-frequency signals up to terahertz ranges while maintaining measurement 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
The MEMS voltmeter provides accurate RMS voltage measurement with high frequency response up to terahertz ranges, overcoming the limitations of existing RMS voltmeters by using electrostatic forces and a rebalancing circuit to maintain balance, enabling precise measurement of high-frequency signals.
Implementation Method 1
For a constant voltage, VK, applied to two plates of a capacitor, the electrostatic force of attraction between these two plates, FK, is the same regardless of the sign of the voltage.
Data Source
AI summary
An electromechanical system (MEMS) voltmeter. An exemplary MEMS voltmeter includes a proof mass mounted to a substrate in a teeter-totter manner. The MEMS voltmeter also includes an input voltage plate located on the substrate under a first end of the proof mass. The first input voltage plate receives a voltage from a device under test. A drive voltage plate is located on the substrate under a second end of the proof mass. A first sense input voltage plate is located on the substrate under the first end of the proof mass. A second sense voltage plate is located on the substrate under the second end of the proof mass. A rebalancing circuit receives signals from the proof mass and the first and second sense voltage plates and generates a voltage value that is equal to the root mean square (RMS) voltage of the device under test.