Philip Mark Garber

US Patent:

7772927, Aug 10, 2010

Filed:

Oct 6, 2008

Appl. No.:

12/245949

Inventors:

Jeffrey B. Shealy - Huntersville NC, US
Philip M. Garber - Huntersville NC, US

Assignee:

RF Micro Devices, Inc. - Greensboro NC

International Classification:

H03F 1/30

US Classification:

330290, 330310

Abstract:

The present invention relates to an active bias Darlington pair amplifier that may operate without a traditional bias resistor. The active bias Darlington pair amplifier includes an output transistor element that is cascaded with and driven from a driver transistor element. Active bias circuitry provides bias to the driver transistor element to regulate bias current in the output transistor element. The bias current in the output transistor element is sensed by the active bias circuitry. The active bias circuitry may include alternating current (AC) circuitry, which may adjust bias under certain radio frequency (RF) drive conditions. The active bias Darlington pair amplifier may include feedback circuitry, which provides feedback from the output transistor element to the driver transistor element. The feedback circuitry may include AC circuitry, which may provide frequency dependent feedback.