A 2.7-5.5 V 0.2-1 W BiCMOS RF driver amplifier IC with closed-loop power control and biasing

GaAs is efficient in realizing RF power amplifiers (PA) at output levels >1 W. However, because GaAs PAs are not compatible with mainstream Si-based technologies, they are difficult to merge with other low-cost functions of a transceiver for a one-chip solution. Integrated PAs with >1 W output are demonstrated in Si-based BiCMOS and CMOS technologies, but because their power-added-efficiency (PAE) is lower than that of GaAs, they are not useful in applications where long battery life is of concern. Here, the problem of low PAE is sidestepped by implementing the final power stage of the amplifier off-chip. Effort is focused on integrating a BiCMOS driver amplifier along with other transmitter support functions not found in a GaAs PA. With this approach, benefits including higher level of functionality, versatile power levels, and low packaging cost are attained without sacrificing PAE.