Variable capacitor, impedance matching device, mobile terminal thereof and method for matching impedance

Patent metadata

Field	Value
Publication number	US-9484880-B2
Application number	US-201113989281-A
Country	US
Kind code	B2
Filing date	Nov 7, 2011
Priority date	Nov 25, 2010
Publication date	Nov 1, 2016
Grant date	Nov 1, 2016

Abstract

Disclosed is an impedance matching device. Variable devices of the impedance matching device installed in a mobile terminal, such as a portable terminal, are configured to have a MEMS structure. The MEMS structure and other components are integrated as one package, so the manufacturing cost is reduced and the manufacturing efficiency is improved.

First claim

The invention claimed is:

1. An impedance matching device comprising:
a substrate;
a variable device unit mounted on the substrate and including at least one MEMS variable capacitor to change a capacitance value according to applied voltage;
a fixed device unit mounted on the substrate and including at least one inductor coupled with the MEMS variable capacitor to form a predetermined time constant;
a reflective power measurement unit mounted on the substrate to measure an intensity of a reflective wave of a signal transmitted from the variable device unit and the fixed device unit; and
a converting unit mounted on the substrate to output a direct current voltage value by converting the intensity of the reflective wave of the signal measured by the reflective power measurement unit into the direct current voltage value;
wherein the MEMS variable capacitor comprises:
a first electrode;
a second electrode floating above the first electrode;
a fixed electrode spaced apart from a lateral side of the second electrode; and
a movable electrode interposed between the second electrode and the fixed electrode and connected to the second electrode to physically make contact with the fixed electrode as voltage is applied to the fixed electrode; and

wherein a first insulating layer is formed on the first electrode to inhibit an electrical short between the first electrode and the second electrode, and a second insulating layer is formed on the fixed electrode to inhibit an electrical short between the fixed electrode and the movable electrode.

2. The impedance matching device of claim 1 , wherein the reflective power measurement unit includes a directional coupler.

3. The impedance matching device of claim 1 , wherein a gap between the first and second electrodes is adjusted by varying voltage applied to the first electrode.

4. The impedance matching device of claim 1 , wherein the first electrode and the fixed electrode are formed on a substrate, and the second electrode and the movable electrode are connected to a spring fixed to the substrate so that the second electrode floats above the first electrode.

5. The impedance matching device of claim 1 , wherein each of the fixed electrode and the movable electrode includes a pair of electrodes or four electrodes located at both sides of the second electrode.

6. The impedance matching device of claim 1 , wherein the second electrode floats above the first electrode by a spring structure.

7. An impedance matching device comprising:
a substrate;
a variable device unit mounted on the substrate and including at least one MEMS variable capacitor to change a capacitance value according to applied voltage;
a fixed device unit mounted on the substrate and including at least one inductor coupled with the MEMS variable capacitor to form a predetermined time constant;
a reflective power measurement unit mounted on the substrate to measure an intensity of a reflective wave of a signal transmitted from the variable device unit and the fixed device unit; and
a converting unit mounted on the substrate to output a direct current voltage value by converting the intensity of the reflective wave of the signal measured by the reflective power measurement unit into the direct current voltage value, wherein the MEMS variable capacitor comprises:
a first electrode;
a second electrode spaced apart from the first electrode;
a third electrode floating above the first and second electrodes;
fourth electrodes connected to the third electrode through a spring structure; and
fifth electrodes formed in opposition to the fourth electrodes and configured to variably adjust a capacitance value of the MEMS variable capacitor;
wherein when a voltage is applied to the fifth electrodes, a distance between the third electrode and the first and second electrodes is increased in response to the applied voltage, and
wherein the third electrode is vertically disposed between the fifth electrode and a collection of the first, second, and fourth electrodes.

8. The impedance matching device of claim 7 , further comprising a support structure to fix a part of the spring structure.

9. The impedance matching device of claim 8 , wherein the spring structure, the support structure, the fourth electrodes and the fifth electrodes are prepared as pairs, respectively, the pair of the spring structures are connected to end portions of both lateral sides of the third electrodes and the pair of the fourth electrodes, parts of the pair of the spring structures are fixed by the pair of the support structures, and the fifth electrodes are aligned in opposition to the fourth electrodes.

10. The impedance matching device of claim 9 , wherein the pair of support structures are driven in a seesaw action as voltage is applied from the fifth electrodes to the fourth electrodes so that the third electrode moves upward from the first and second electrodes.

Assignees

• Kim Chang Wook
• Lg Innotek Co Ltd

Inventors

• Kim Chang Wook

Classifications

• H01G7/00

  Capacitors in which the capacitance is varied by non-mechanical means; Processes of their manufacture · CPC title

• H03H2007/008

  the MEMS being trimmable · CPC title

• H03H7/38 Primary

  Impedance-matching networks · CPC title