Composite Crystal Resonator Circuit for Vibration-Stable Oscillators
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Solution Overview
Problem
Current technologies face challenges in achieving high-quality inductors on integrated circuit substrates due to low resistivity, which affects resonance frequencies and timing circuit operations, and also struggle with sensitivity to acceleration and vibration forces in oscillator circuits.
Innovation Solution
The integration of serially-connected crystal resonators with a temperature-compensated, CMOS-based negative impedance converter (NIC) and an acceleration vector weighting circuit, which are programmable to mimic negative capacitive reactance and reduce sensitivity to acceleration forces, is implemented within a sealed cavity package.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional wafer-scale fabrication techniques are used to form inductors on integrated circuit substrates, then manufacturing complexity is reduced, but the quality factor (Q) of the inductors is insufficient due to low resistivity and surrounding lossy materials
Solution Approach 1:
The patent introduces a negative impedance converter (NIC) circuit as an intermediary element that electrically compensates for the lossy environment. The NIC generates a negative resistance that cancels out the positive resistance from the substrate and surrounding materials, thereby improving the effective Q factor of the inductor without requiring changes to the fabrication process or substrate materials.
Solution Approach 2:
The patent changes the electrical parameters of the oscillator circuit by using the NIC to alter the effective impedance seen by the inductor. By programmatically adjusting the NIC's output impedance, the system can compensate for variations in substrate resistivity and optimize the inductor Q factor for different operating conditions.
2Stability of the object's composition
If crystal resonators are used in oscillator circuits, then frequency stability is improved, but sensitivity to acceleration and vibration forces increases
Solution Approach 1:
The patent employs multiple crystal resonators oriented in different directions with their acceleration sensitivity vectors arranged in an anti-parallel relationship. The sensitivity effects of individual resonators counterbalance each other, canceling out the harmful effects of acceleration and vibration while maintaining frequency stability.
Solution Approach 2:
The patent integrates multiple functions into the oscillator circuit: frequency generation, temperature compensation, and acceleration sensitivity cancellation. By combining multiple resonators with different orientations and using programmable NIC circuits, the system achieves both frequency stability and reduced vibration sensitivity simultaneously.
3Stability of the object's composition
If temperature compensation circuits are added to MEMs resonators, then frequency stability is improved, but device complexity increases
Solution Approach 1:
The patent combines the temperature compensation function with the existing NIC circuit used for inductor Q enhancement. The same NIC circuit is programmatically configured to provide both impedance transformation and temperature compensation, eliminating the need for separate compensation circuits and reducing overall device complexity.
Solution Approach 2:
The NIC circuit serves multiple functions: it enhances the inductor Q factor, provides temperature compensation for the resonators, and enables programmable optimization of oscillator performance. This multi-functionality reduces the need for additional dedicated circuits.
4Object-affected harmful factors
If multiple crystal resonators are used to reduce acceleration sensitivity, then vibration resistance is improved, but device complexity increases
Solution Approach 1:
The patent uses crystal resonators with different orientations and configurations, deliberately creating an asymmetric arrangement where the acceleration sensitivity vectors are anti-parallel. This asymmetric configuration is optimized to cancel vibration effects while maintaining a relatively simple overall structure.
Solution Approach 2:
The patent uses multiple copies of crystal resonator elements with different orientations. By replicating the resonator structure in different spatial configurations, the system achieves vibration cancellation through the collective behavior of the resonator array rather than requiring a completely different design approach.
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 configuration enhances the quality of resonance and reduces sensitivity to acceleration forces, leading to improved frequency stability and reduced power consumption in oscillator circuits.
Implementation Method 1
a crystal oscillator device containing a piezoelectric resonator element
Implementation Method 2
a first negative impedance converter (NIC) having an input terminal electrically connected to an input terminal of the first crystal resonator
Implementation Method 3
a pair of serially-connected resonators including a first resonator configured to generate a fundamental frequency and a second resonator configured to generate a third or higher overtone frequency
Data Source
AI summary
An integrated circuit device includes a pair of serially-connected crystal resonators arranged as a first crystal resonator, which is configured to preferentially support a fundamental resonance mode in response to an input signal, and a second crystal resonator, which is configured to preferentially support a third or higher overtone resonance mode in response to a signal generated at an output terminal of the first crystal resonator. A negative impedance converter (NIC) is also provided, which has an input terminal electrically connected to an input terminal of the first crystal resonator and an output terminal electrically connected to one of the output terminal of the first crystal resonator and the output terminal of the second crystal resonator. The NIC may be a CMOS-based NIC that is devoid of inductive reactance from a passive inductor.