Dan Y Hu

US Patent:

60640677, May 16, 2000

Filed:

Apr 13, 1998

Appl. No.:

9/059732

Inventors:

Yang Zhao - Novi MI
Dan Hu - Detroit MI

Assignee:

Wayne State University - Detroit MI

International Classification:

G01N 2162

US Classification:

250353

Abstract:

An infrared collector employs a concentrator formed of a plurality of spatially related gradient-indexed (GRIN) lenses and a photodetector, interconnected by optical fibers. Since the GRIN lenses are arranged on a hemispherical shell, the concentrator is relatively insensitive to the direction of the incoming infrared radiation. Optical fibers are used to connect the GRIN lenses to a photodetector, whereby assembly is simplified. The infrared detector in the collector of the present invention has a size that is significantly smaller than those used in conventional collectors. The concentrator has high optical gain, and therefore, is particularly well adapted for use in low-power portable systems. The arrangement is useful as a node in an infrared data network.

US Patent:

59907088, Nov 23, 1999

Filed:

Jan 30, 1998

Appl. No.:

9/016033

Inventors:

Dan C. Hu - Bellaire TX

Assignee:

Texas Instruments Incorporated - Dallas TX

International Classification:

H03K 522

US Classification:

327 68

Abstract:

A differential input buffer (14) and method of construction are provided. The differential input buffer (14) includes a differential amplifier (54, 56, 50, 52, 62, 64) connected to receive an input signal (IN). A local reference voltage generator (68, 70, 72) is connected to the differential amplifier (54, 56, 50, 52, 62, 64) and is connected to receive an external voltage reference (BLR) and to provide a local reference voltage (VREF) to the differential amplifier (54, 56, 50, 52, 62, 64). The local reference generator (68, 70, 72) is adjustable during construction to produce a desired level for the local reference voltage (VREF). The differential input buffer (14) also includes a hysteresis element (66, 74) that is connected to provide feedback to the differential amplifier (54, 56, 50, 52, 62, 64) and includes a buffer stage (76, 78, 80, 82, 84, 86) that is connected to receive an output of the differential amplifier (54, 56, 50, 52, 62, 64) and to drive an output signal (OUT). The buffer stage is also connected to the hysteresis element (66, 74) to provide a basis for the feedback to the differential amplifier (54, 56, 50, 52, 62, 64).