Peter K Cheung

US Patent:

6922103, Jul 26, 2005

Filed:

May 21, 2003

Appl. No.:

10/442596

Inventors:

Peter Y. Cheung - Chino Hills CA, US
David L. Crampton - Rossmoor CA, US
Jennifer Y. Vollbrecht - Torrance CA, US
Kuang Yung Liu - Los Angeles CA, US
Lauriston Chin Wah - Manhattan Beach CA, US

Assignee:

The Boeing Company - Chicago IL

International Classification:

H03F001/26

US Classification:

330149, 330151

Abstract:

A method and apparatus for reducing intermodulation distortion is disclosed. In one embodiment, the method comprises the steps of accepting a sampled input signal V(t) wherein the input signal V(t) comprises a plurality of peaks; determining n peaks V,V,. . . Vof the sampled input signal V(t) exceeding a clip value Vat times t, t,. . . t; and modifying the sampled input signal V(t) by weighting the n peaks V,V,. . . ,Vexceeding the clip value Vof the sampled input signal V(t) by a function b(t) wherein b(t) is either a hard limiting function or b(t)=f(a, a,. . . a;t−t,t−t,. . . t−t), wherein a,a,. . . aare weight values corresponding to the n peaks V, V,. . . V, and f(t−t,t−t,. . . t−t) is a smooth shaping function. Intermodulation performance is then selectively improved in selected sub-bands by notch filtering prior to application to the non-linearity.

US Patent:

20060088321, Apr 27, 2006

Filed:

Oct 25, 2004

Appl. No.:

10/973857

Inventors:

Peter Cheung - Chino Hills CA, US
James Dupont - Lomita CA, US
Lauriston Wah - Manhattan Beach CA, US
Gilbert Yu - Rancho Palos Verdes CA, US

International Classification:

H04B 10/04

US Classification:

398195000

Abstract:

A method and system are provided for using a power spectral density of an output of a modulator to facilitate closed loop feedback for controlling alignment of a pulse with respect to information formed upon the pulse.

US Patent:

61226890, Sep 19, 2000

Filed:

May 13, 1998

Appl. No.:

9/078346

Inventors:

Peter K. Cheung - Milpitas CA

Assignee:

Adaptec, Inc. - Milpitas CA

International Classification:

G06F 1300

US Classification:

710101

Abstract:

Disclosed is a host adapter having automatic termination, and a method for implementing the automatic termination. The host adapter includes a first connector for connecting to at least one external peripheral device and a second connector for connecting to at least one internal peripheral device. The host adapter further includes a termination system circuit that is coupled between the first connector and the second connector. The termination system circuit is configured to produce bit data that is indicative of whether a peripheral device is coupled to one or both of the first connector and the second connector. Preferably, the termination system circuit communicates the bit data to a software termination engine upon boot-up to enable or disable a termination of the host adapter. Furthermore, the termination system circuit includes a termination control decoder and a tri-state buffer. The host adapter also includes a termination over-ride control that is configured to over-ride the automatic termination generated by the termination system circuit via a software control.

US Patent:

61540676, Nov 28, 2000

Filed:

Aug 5, 1998

Appl. No.:

9/130196

Inventors:

Peter K. Cheung - Milpitas CA

Assignee:

Adaptec, Inc. - Milpitas CA

International Classification:

H03K 522
H03K 5153

US Classification:

327 74

Abstract:

When more than two terminators are on a SCSI bus the bus is said to be "over-terminated", and when less than two terminators are on the bus, the bus is said to be "under-terminated". When the SCSI bus is either under or over terminated, the bus does not function, and often the user does not know why the bus is not functioning. Apparatus and a method are provided for indicating to the user when the bus is not properly terminated. A terminator monitoring system and method operate in conjunction with the bus. A precision resistor is connectable to the bus so that a voltage drop is produced across the precision resistor. A circuit monitors the value of the produced voltage drop across the precision resistor to provide an indication of the number of terminators on the bus. A switch selectably connects the precision resistor to the bus, and there is a source of a reference voltage. The monitoring circuit includes a comparison circuit responsive to the voltage drop across the precision resistor and to the reference voltage for indicating whether the number of terminators on the bus exceeds a limit or is less than the limit.

US Patent:

6173344, Jan 9, 2001

Filed:

May 27, 1998

Appl. No.:

9/085671

Inventors:

Abdul Waheed Mohammed - Sunnyvale CA
Peter K. Cheung - Milpitas CA
Barry Davis - Union City CA
Christopher Burns - San Jose CA

Assignee:

Adaptec, Inc - Milpitas CA

International Classification:

G06F 1300

US Classification:

710 62

Abstract:

Disclosed is a SCSI host adapter for use in a computer system. The SCSI host adapter is configured to provide the computer system with interconnection with internal and/or external target devices. The SCSI host adapter includes a low voltage differential connector for interconnecting to a low voltage differential bus, and the low voltage differential bus is configured to communicate a first transaction. The SCSI host adapter also includes a single ended connector for interconnecting to a single ended bus, and the single ended bus is configured to communicate a second transaction. Furthermore, the SCSI host adapter includes a transceiver unit that is configured to interface between the low voltage differential bus and the single ended bus and produce a target information signal. The target information signal is configured to indicate whether the first transaction or the second transaction is occurring between the SCSI host adapter and the low voltage differential bus or the single ended bus.