Feng Chen

US Patent:

7057540, Jun 6, 2006

Filed:

Oct 17, 2002

Appl. No.:

10/273217

Inventors:

Khurram Muhammad - Dallas TX, US
Robert B. Staszewski - Garland TX, US
Feng Chen - Plano TX, US
Dirk Leipold - Plano TX, US

Assignee:

Texas Instruments Incorporated - Dallas TX

International Classification:

H03M 3/00

US Classification:

341143, 341155

Abstract:

A sigma-delta analog-to-digital converter-offers advantages such as noise shaping and high frequency operation. However, a sampling circuit needed to provide a highly oversampled discrete-time sample stream with low noise characteristics is difficult to design and implement. The present invention provides a sigma-delta mixer with such a sampling circuit. The present invention discloses a sampling circuit using switched capacitors , and with low noise characteristics and at the same time is capable of providing a highly oversampled discrete-time sample stream.

US Patent:

7079826, Jul 18, 2006

Filed:

Mar 15, 2002

Appl. No.:

10/099831

Inventors:

Khurram Muhammad - Dallas TX, US
Dirk L. Leipold - Plano TX, US
Feng Chen - Plano TX, US
Kenneth J. Maggio - Dallas TX, US

Assignee:

Texas Instruments Incorporated - Dallas TX

International Classification:

H04B 1/06

US Classification:

455262, 455257, 455118, 455137

Abstract:

A first periodic voltage waveform () is downconverted into a second periodic voltage waveform (). A plurality of temporally distinct samples (SA, SA,. . . ) respectively indicative of areas under corresponding half-cycles of the first voltage waveform are obtained. The samples are combined to produce the second voltage waveform, and are also manipulated to implement a filtering operation such that the second voltage waveform represents a downconverted, filtered version of the first voltage waveform.