Sheldon X Xu

US Patent:

7248111, Jul 24, 2007

Filed:

Apr 14, 2005

Appl. No.:

11/106254

Inventors:

Sheldon Xu - Edison NJ, US
Thomas William Arell - Basking Ridge NJ, US
Mahendra Singh - Bridgewater NJ, US
Mohammed Ali Khatibzadeh - Hampton NJ, US

Assignee:

Anadigics, Inc - Warren NJ

International Classification:

H03G 5/16

US Classification:

330133, 330285, 330296, 330310

Abstract:

A power amplifier with a multi-mode digital bias control circuit is provided. The power amplifier utilizes a complementary reference voltage generation circuit and a bias current-control circuit to generate a plurality of bias current levels for different output power levels. In an embodiment of the present invention, the power amplifier circuit is connected to a reference voltage and two control signals. Depending on the desired output power level, the control signals set the corresponding bias current in the amplifying transistors, to ensure sufficient linearity. The power amplifier is capable of operating at a very low quiescent current level, for example, 5 mA. As a result, a significant improvement in the power amplifier's overall efficiency is achieved, and the battery talk time of a wireless communication device is increased. The invention finds application in wireless communication devices such as CDMA, WCDMA, EDGE and WLAN mobile devices.

US Patent:

20030214365, Nov 20, 2003

Filed:

May 20, 2002

Appl. No.:

10/147987

Inventors:

Aharon Adar - Berkeley Heights NJ, US
Sheldon Xu - Somerville NJ, US

International Classification:

H01P005/18

US Classification:

333/109000, 333/101000

Abstract:

The present invention discloses a miniature high directivity multi-band coupled-line coupler for RF power amplifier module application. The coupler utilizes a three-coupled-line structure, with a first RF line designated coupled line for the GSM 900 MHZ band, a second RF line designated coupled line for the DCS/PCS 1800/1900 MHZ band, and a common coupled line. A first capacitor is connected between the center of the first line and the center of the common line and a second capacitor is connected between the center of the second line and the center of the common line. The coupler has a length considerably less than the length of a quarter wave length coupler while achieving directivity requirements for both GSM band and DCS/PCS band.