Shape-Memory Adjustable Capacitor for Wide-Range Low-Voltage Tuning
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Solution Overview
Problem
Existing adjustable capacitors, such as varactors, require significant voltage changes to achieve sufficient capacitance variation, posing a technical challenge in achieving precise and wide-range capacitance adjustments.
Innovation Solution
The proposed adjustable capacitor incorporates a base substrate with capacitor units featuring first and second plates connected by elastic components. These elastic components, made of shape memory alloy, deform in response to temperature changes, altering the overlapping area of the plates and thus the capacitance value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If varactors are used as adjustable capacitors, then the device can provide capacitance adjustment, but a significant change in voltage is required to achieve sufficient change in capacitance
Solution Approach 1:
The patent replaces the electrical field-based varactor mechanism with a mechanical field-based MEMS structure. The movable electrode is physically displaced by applying voltage to create electrostatic force, directly changing the capacitance through mechanical movement rather than relying on voltage-induced changes in barrier capacitance. This mechanical substitution enables larger capacitance changes with smaller driving voltages.
Solution Approach 2:
The patent introduces a movable electrode that can dynamically change its position relative to the fixed electrode. By making one electrode movable rather than fixed, the system can dynamically adjust capacitance values over a wide range by controlling the distance between electrodes through electrostatic actuation, achieving both wide adjustment range and low driving voltage.
2Ease of operation
If varactors are used for capacitance adjustment, then the device can function in tuning circuits, but noise is not reduced
Solution Approach 1:
The patent replaces the electrical field-based varactor with a mechanical field-based MEMS capacitor. The mechanical movement of the electrode in response to electrostatic forces provides tuning capability while the physical separation and controlled movement reduce noise generation compared to the electrical field effects in varactors.
3Adaptability or versatility
If traditional adjustable capacitors are used, then capacitance can be adjusted, but the adjustment range is limited
Solution Approach 1:
The patent divides the capacitor into two distinct parts: a fixed electrode and a movable electrode. This segmentation allows independent optimization of each part's function and enables wide capacitance adjustment range through the relative movement between the two segments, while keeping the overall structure relatively simple.
Solution Approach 2:
The patent introduces a movable electrode that can dynamically change position to achieve wide capacitance adjustment range. The dynamic structure allows capacitance to be varied by changing the distance between electrodes, providing adaptability without requiring complex multi-component systems.
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 design allows for precise and wide-range capacitance adjustments by mechanically tuning the capacitor units, reducing noise and requiring lower driving voltages compared to traditional varactors.
Implementation Method 1
the first elastic component is made of a shape memory alloy and is configured to deform in response to a temperature change
Implementation Method 2
the first elastic sub-member is configured to stretch or contract along the first direction in response to that the operating environment reaches a specific temperature
Data Source
AI summary
The present disclosure provides an adjustable capacitor and an electronic apparatus, and relates to the technical field of radio frequency device. The adjustable capacitor of the present disclosure includes a base substrate and at least one capacitor unit on the base substrate, each of the at least one capacitor unit includes a first plate, a second plate and a first connecting arm; the first plate and the connecting arm are on the base substrate; one end of the second plate is connected to the first connecting arm, the second plate and the first plate are opposite to each other, and a certain distance is between the second plate and the first plate.