David Jun Chu

US Patent:

6480126, Nov 12, 2002

Filed:

Oct 26, 2001

Appl. No.:

10/003798

Inventors:

David C. Chu - Palo Alto CA

Assignee:

Agilent Technologies, Inc. - Palo Alto CA

International Classification:

H03M 148

US Classification:

341111

Abstract:

A system and method of digitizing characteristic parameters of a quasi-sinusoidal analog signal of unknown magnitude, frequency and phase-offset, includes digitizing the analog signal at a first sampling rate, thereby generating a plurality of sets of digital signal waveform samples. Successive sets of the digital signal waveform samples are digitally processed to generate continually updated digital characteristic parameters representing a characteristic behavior of the quasi-sinusoidal analog signal.

US Patent:

6738143, May 18, 2004

Filed:

Nov 13, 2001

Appl. No.:

10/010175

Inventors:

David C. Chu - Palo Alto CA

Assignee:

Agilent Technologies, Inc - Palo Alto CA

International Classification:

G01B 902

US Classification:

356450, 356484, 356496

Abstract:

A system and method for non-linearity compensating interferometer position data includes receiving a plurality of groups of digital position values. A first group of the digital position values are digitally processed to generate a plurality of data values. The plurality of data values are digitally processed to generate at least one quasi-static non-linearity parameter. A second group of the digital position values are compensated based on the at least one non-linearity parameter.

US Patent:

6792368, Sep 14, 2004

Filed:

Jan 17, 2002

Appl. No.:

10/052673

Inventors:

David C. Chu - Palo Alto CA

Assignee:

Agilent Technologies, Inc. - Palo Alto CA

International Classification:

G01C 1738

US Classification:

702 94

Abstract:

A system and method for compensating non-linearity of the high-velocity type manifested in heterodyne interferometer position data includes receiving a plurality of groups of digital position values. A plurality of groups of digital phase values from a measurement channel are received. A first group of the digital position values and digital phase values are digitally processed to generate a plurality of block data values. The plurality of block data values are digitally processed to generate at least one quasi-static non-linearity parameter. A second group of the digital position values are compensated based on the at least one quasi-static non-linearity parameter.

US Patent:

6952175, Oct 4, 2005

Filed:

Sep 23, 2003

Appl. No.:

10/668851

Inventors:

David C. Chu - Palo Alto CA, US
Carol Joann Courville - San Jose CA, US
Lee C. Kalem - Los Gatos CA, US

Assignee:

Agilent Technologies, Inc. - Palo Alto CA

International Classification:

H03M001/48

US Classification:

341111

Abstract:

A method of digitizing first and second signals in imperfect quadrature for obtaining characteristic parameters of the first signal comprises providing a first signal, the first signal comprising an inphase quasi-sinusoidal analog signal. The method comprises providing a second signal, the second signal comprising a quadrature signal. The method comprises digitizing the first signal at a sampling rate, thereby generating a first plurality of sets of digital signal waveform samples and digitizing the second signal at the sampling rate, thereby generating a second plurality of sets of digital signal waveform samples. The method comprises digitally processing successive first and second sets of digital signal waveform samples to generate continually updated digital characteristic parameters representing a characteristic behavior of the first signal.

US Patent:

7130056, Oct 31, 2006

Filed:

Feb 20, 2004

Appl. No.:

10/783199

Inventors:

William Clay Schluchter - Los Altos CA, US
Louis F. Mueller - Palo Alto CA, US
Douglas P. Woolverton - Mountain View CA, US
Jeffrey A. Young - Campbell CA, US
Alan B. Ray - Palo Alto CA, US
David C. Chu - Palo Alto CA, US

Assignee:

Agilent Technologies, Inc. - Palo Alto CA

International Classification:

G01B 11/02

US Classification:

356500

Abstract:

A system and method for acquiring position information of a movable apparatus relevant to a specific axis is disclosed. In one embodiment, an interferometer generates first and second beams and various beam-steering members are located to define beam path segments for the two beams, but no beam path segment varies in length in unity with displacements of the movable apparatus along the specific axis. In another or the same embodiment, each beam path segment in which the first beam either impinges or has been reflected from the movable apparatus is symmetrical to a corresponding beam path segment of the second beam. The movable apparatus may be a wafer stage in which the “specific axis” is the exposure axis of a projection lens, but with all optical members which cooperate with the stage being located beyond the ranges of the wafer stage in directions perpendicular to the lithographic exposure axis.

US Patent:

7230727, Jun 12, 2007

Filed:

Apr 22, 2005

Appl. No.:

11/112623

Inventors:

David C. Chu - Palo Alto CA, US
Evan R. Whitney - Saratoga CA, US

Assignee:

Agilent Technologies, Inc. - Santa Clara CA

International Classification:

G01B 11/14

US Classification:

356616, 356420, 356421

Abstract:

A system for sensing an absolute position in two dimensions includes a target having a two-dimensional target pattern. A sensor captures an image of a first subset of the target pattern. A controller generates a first image vector representing summations of rows of pixel values from the image, and a second image vector representing summations of columns of pixel values from the image. The controller is configured to determine an absolute two-dimensional position of the first subset with respect to an origin of the target pattern based on the first and the second image vectors and a plurality of target vectors that represent the target pattern.

US Patent:

7489409, Feb 10, 2009

Filed:

May 24, 2007

Appl. No.:

11/753508

Inventors:

David C. Chu - Palo Alto CA, US
Evan R. Whitney - Saratoga CA, US

Assignee:

Agilent Technologies, Inc. - Santa Clara CA

International Classification:

G01B 11/14

US Classification:

356614, 356616

Abstract:

A system for sensing an absolute two-dimensional position of an object having a two-dimensional target pattern thereon comprises a sensor and a controller. The sensor is for capturing an image of a subset of the target pattern. The controller is for generating a first image vector representing summations of rows of pixel values from the image, and a second image vector representing summations of columns of pixel values from the image. The controller is configured to determine an absolute two-dimensional position of the subset of the target pattern with respect to the origin of the target pattern based on the first image vector, the second image vector and target vectors that represent the target pattern.

US Patent:

7622945, Nov 24, 2009

Filed:

Dec 20, 2006

Appl. No.:

11/614031

Inventors:

Christopher Cheng - Cupertino CA, US
David Chu - Santa Clara CA, US

Assignee:

3PAR, Inc. - Fremont CA

International Classification:

H03K 19/003

US Classification:

326 21, 326 31, 326 82

Abstract:

A method for a mix mode driver to accommodate traces of different lengths includes sequentially shifting values of a data signal to a number of stages and sequentially amplifying the values of the data signal at least one stage. Depending on the length of trace for the data signal, the method further includes providing at least one amplifying coefficient to at least one stage and coupling a subset of the stages to an adder. The method finally includes outputting the data signal from the adder to the trace.