Apparatus and method for driving MEMS structure and detecting motion of the driven MEMS structure using a single electrode

• US 20050132806A1
• Filed: 12/22/2004
• Published: 06/23/2005
• Est. Priority Date: 12/22/2003
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Lee, Sang-woo, Kim, Jong-pal, Lee, Byeung-Ieul
• Granted Patent: US 7,178,397 B2
• Time in Patent Office: Days
• US Class Current: 73/514.320
• CPC Class Codes: G01C 19/5776 Signal processing not specific to any of the devices covered by groups G01C19/5607 - G01C19/5719

Abstract

Apparatus and a method for driving and detecting a motion of MEMS structure using single electrode. Apparatus includes a driving signal generation part driving MEMS structure; a motion detection part detecting motion of MEMS structure and outputting a motion current signal; an amplification part amplifying motion current signal and outputting a motion voltage signal; a gain adjustment part amplifying driving signal and outputting an amplified driving signal; a differential circuit part adding and subtracting with respect to signals output from the amplifying part and the gain adjustment part and outputting a motion signal without the driving signal; and a motion signal detection part selecting and outputting a motion signal of a predetermined frequency from the motion signal output from the differential circuit part. The variable capacitor is configured by a movable electrode plate integrally formed with MEMS structure and a fixed electrode plate disposed opposite to the movable electrode plate.

Claims

1. An apparatus for driving a MEMS (Micro Electro Mechanical System) structure and detecting motion of the driven MEMS structure using a single electrode, comprising:

a driving signal generation part for generating and outputting a first driving signal to drive the MEMS structure;

a motion detection part comprising a variable capacitor, for detecting the motion of the MEMS structure driven according to the first driving signal and outputting a motion current signal corresponding to the motion of the MEMS structure;

an amplification part for amplifying the motion current signal output from the motion detection part and outputting a motion voltage signal;

a gain adjustment part for amplifying the first driving signal input from the driving signal generation part and outputting a second driving signal amplified by a predetermined gain;

a differential circuit part for performing adding and subtracting operations with respect to the motion voltage signal output from the amplifying part and the second driving signal output from the gain adjustment part and outputting a motion signal without the second driving signal; and

a motion signal detection part for selecting and outputting a motion signal of a predetermined frequency out of the motion signal output from the differential circuit part.

2. The apparatus as claimed in claim 1, wherein the variable capacitor comprises a movable electrode plate integral to the MEMS structure and supplied with the first driving signal and a fixed electrode plate disposed opposite to the movable electrode plate and virtually grounded.

3. The apparatus as claimed in claim 2, wherein the amplification part comprises:

an amplifier having a negative input terminal connected to the fixed electrode plate, a positive terminal connected to a grounded electrode, and an output terminal; and

a first capacitor connected to the amplifier in parallel.

4. The apparatus as claimed in claim 1, wherein the variable capacitor comprises a movable electrode plate integral to the MEMS structure and grounded, and a fixed electrode plate disposed opposite to the movable electrode plate and supplied with the first driving signal.

5. The apparatus as claimed in claim 4, wherein the amplification part comprises:

an amplifier having a negative input terminal connected to the fixed electrode plate, a positive input terminal connected to the driving signal generation part, and an output terminal; and

a second capacitor connected to the amplifier in parallel.

6. The apparatus as claimed in claim 1, wherein the motion signal detection part is a band pass filter.

7. The apparatus as claimed in claim 1, wherein the gain adjustment part is an amplifier for amplifying the first driving signal to an amplitude of a third driving signal included in the motion signal output from the amplification part.

8. A method for driving a MEMS (Micro Electro Mechanical System) structure and detecting motion of the driven MEMS structure using a single electrode, comprising:

generating and outputting a first driving signal to drive the MEMS structure;

detecting the motion of the MEMS structure driven according to the first driving signal with a variable capacitor and outputting a motion current signal corresponding to the motion of the MEMS structure;

amplifying the motion current signal and outputting a motion voltage signal;

amplifying the first driving signal input and outputting a second driving signal amplified by a predetermined gain;

performing adding and subtracting operations with respect to the motion voltage signal and the second driving signal and outputting a motion signal without the second driving signal; and

selecting and outputting a motion signal of a predetermined frequency from the motion signal.

9. The method as claimed in claim 8, wherein the variable capacitor comprises a movable electrode plate integral to the MEMS structure and supplied with the first driving signal and a fixed electrode plate disposed opposite to the movable electrode plate and virtually grounded.