MEMS Resonator Voltage Reference for Radiation Hardness
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Solution Overview
Problem
Current radiation-hard voltage references based on electrical components like diodes and transistors fail to provide the necessary stability and radiation hardness for high-performance inertial instruments, especially in high-altitude flight and outer space environments.
Innovation Solution
A Precision Voltage Reference (PVR) is developed using a Micro-Electro-Mechanical System (MEMS) resonator, which is inherently radiation-hard, utilizing a converter to receive a reference voltage based on the resonator's oscillation frequency and applying a bias voltage to stabilize the oscillation frequency, thereby achieving high stability and desensitizing the system to trapped charge and DC offset voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If radiation-hard voltage references are based on electrical components like diodes and transistors, then radiation hardness is improved, but stability deteriorates
Solution Approach 1:
The patent replaces electrical components (diodes, transistors) with a mechanical resonator system. The resonator uses proof masses, springs, and dampers to create a mechanical oscillation whose frequency is used to generate the voltage reference. This mechanical substitution eliminates the radiation sensitivity of semiconductor components while maintaining voltage stability through the mechanical resonance frequency.
Solution Approach 2:
The patent changes the fundamental parameter basis from electrical properties to mechanical properties. The voltage reference stability is derived from the mechanical resonator's natural frequency, which is determined by physical dimensions, mass, and stiffness parameters that are inherently radiation-hard. The bias voltage is adjusted to maintain the resonator at its natural frequency, providing radiation-hard stability.
2Reliability
If a MEMS resonator is used for the PVR, then radiation hardness is improved, but device complexity increases
Solution Approach 1:
The patent merges the resonator structure with the voltage reference generation function. The mechanical resonator itself serves as both the frequency reference and the basis for voltage generation through its interaction with the bias voltage. This integration reduces overall device complexity by combining multiple functions into a single resonator-based system.
Solution Approach 2:
The resonator system is self-regulating through its natural mechanical resonance. The proof masses, springs, and dampers create a self-sustaining oscillation that automatically maintains its frequency characteristics. The system uses its own mechanical properties to generate the reference signal without requiring external calibration or adjustment mechanisms.
3Stability of the object's composition
If bias voltage is applied to stabilize oscillation frequency, then voltage stability is improved, but sensitivity to trapped charge and DC offset voltages increases
Solution Approach 1:
The patent applies periodic AC bias voltage signals to the resonator rather than continuous DC bias. This periodic action causes the resonator to oscillate at its natural frequency, and the frequency measurement is used to generate the stable voltage reference. The periodic nature of the excitation makes the system insensitive to DC offset voltages and trapped charge effects, as these only affect the amplitude not the frequency of oscillation.
Solution Approach 2:
The patent converts the potential harmful effect of trapped charge and DC offsets into a beneficial feature. By using frequency-based measurement rather than amplitude-based measurement, the system makes the harmful factors irrelevant to the reference output. The trapped charge and DC offsets affect only the oscillation amplitude, which is discarded, while the frequency remains pure and unaffected, providing inherent rejection of these harmful factors.
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-based Radiation-Hard Precision Voltage Reference (RHPVR) achieves improved radiation hardness and stability, approaching 1 ppm in nuclear radiation environments, enabling reliable performance in strategic guidance applications by periodically altering the bias voltage polarity and eliminating the effects of trapped charge and DC offset voltages.
Implementation Method 1
a resonator having an oscillation frequency, the resonator including a first proof-mass, a first forcer located adjacent a first side of the first proof-mass, and a second forcer located adjacent a second side of the first proof-mass
Implementation Method 2
provide a first bias voltage to the first forcer based on the reference voltage, provide a second bias voltage to the second forcer based on the reference voltage
Implementation Method 3
periodically alter a polarity of the first bias voltage and the second bias voltage to drive the oscillation frequency of the resonator to match a reference frequency
Data Source
AI summary
Provided is a Precision Voltage Reference (PVR). In one example, the PVR includes a resonator having an oscillation frequency, the resonator including a first proof-mass, a first forcer located adjacent a first side of the first proof-mass, and a second forcer located adjacent a second side of the first proof-mass. The PVR may include control circuitry configured to generate a reference voltage based on the oscillation frequency of the resonator, at least one converter configured to receive the reference voltage from the control circuitry, provide a first bias voltage to the first forcer based on the reference voltage, provide a second bias voltage to the second forcer based on the reference voltage, and periodically alter a polarity of the first and second bias voltages to drive the oscillation frequency to match a reference frequency, and an output configured to provide the reference voltage as a voltage reference signal.