MEMS (micro-electromechanical system) variable capacitor with linear C-V (capacitance-voltage) characteristic and low-stress double-lever structure

Abstract

The invention relates to an MEMS (micro-electromechanical system) variable capacitor with a linear C-V (capacitance-voltage) characteristic and a low-stress double-lever structure. The MEMS variable capacitor is characterized in that a lower polar plate, driving electrodes and anchor points are arranged on a dielectric substrate, two ends of an upper polar plate are fixedly supported on the anchor points by the aid of torsion beams, the middle of the upper polar plate corresponds to the lower polar plate, and the ends of the upper polar plate correspond to the driving electrodes; when linear additional voltages are exerted on the driving electrodes, the ends of the upper polar plate move downwardly, the middle of the upper polar plate moves upwardly, and a capacitance value between the upper polar plate and the lower polar plate is decreased; when the linear additional voltages stop being exerted on the driving electrodes, an initial horizontal state of the upper polar plate is restored via torsion elastic force of the torsion beams, the outer ends of the upper polar plate move downwardly to drive the upper polar plate to move upwardly, the distance from the upper polar plate to the lower polar plate is increased, and the capacitance value C is linearly decreased along with increase of a voltage value. The MEMS variable capacitor has the advantages that the initial distance from the upper polar plate to the lower polar plate is decreased owing to a stepped structure of the middle of the upper polar plate, so that an initial capacitance value is increased, the capacitance variation range is enlarged, and stress generated by deformation when the upper polar plate moves can be released advantageously.

Description

technical field [0001] The invention relates to a low-stress double-lever structure MEMS varactor with linear C-V characteristics, which belongs to the technical fields of electronic circuit technology and micro-electromechanical system (MEMS). Background technique [0002] The radio frequency (RF) variable capacitor designed and manufactured by microelectromechanical system (MEMS) technology has unique advantages such as low insertion loss, high Q value, high linearity, and wide adjustment range. MEMS variable capacitor is one of the basic components of electronic circuit systems such as wireless communication. It is widely used in the front end of wireless communication systems. With miniaturization, high linearity and tunability as the technical development direction, the new generation of information technology is calling for a new generation of high performance components. Compared with traditional varactor diodes, MEMS variable capacitors have the advantages of low in...

AI Technical Summary

Problems solved by technology

At present, there are two basic forms of MEMS adjustable capacitors. One is to adjust the distance between the upper and lower capacitor plates to change the capacitance value. This kind of adjustable capacitor has sensitive response, high Q value and small size, but it has a distance adjustment range. The range of movement of the upper plate cannot be greater than one-third of the initial distance between the upper and lower plates, otherwise the upper plate of the capacitor will be pulled down rapidly, so the adjustable range is small; the other is to adjust the facing area of ​​the capacitor. To change the capacitance value, it is typical to use the finger-like structure to change the capacitance value by changing the facing area between the fingers. This structure has complicated manufacturing process, limited capacitance value, and poor control accuracy of the capacitance.

Usually, the variable capacitor is nonlinear with the change of the control voltage, which greatly increases the complexity of the capacitor control circuit, and the accuracy is easily affected by the noise in the control circuit.

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