High efficiency 28V class AB InGaP/GaAs HBT MMIC amplifier with integrated bias circuit

InGaP/GaAs HBTs have demonstrated excellent lifetime and linearity performance for 3 to 10 V operation. This is very attractive for infrastructure applications. However, the low voltage is a drawback in this application where 28 V is a common voltage used. In this effort, a high voltage InGaP/GaAs HBT is developed for 28 V operation. The safe operation area is carefully designed, allowing the device to function in class A mode. A thermal resistance of 30/spl deg/C/W for a 1 W HBT design is measured using the V/sub be/ method. 4 W CW power with 71% efficiency is measured from this 1 W design, with a junction temperature rise of 49/spl deg/C. The integrated temperature compensated bias circuit provides <9% quiescent current change over base plate temperatures from -40 to +85/spl deg/C. Two tone and CDMA2000 linearity is also characterized. Initial WLR (wafer level reliability) results indicate that it has a similar lifetime to the standard InGaP/GaAs HBT.