900 MHz CMOS single-ended power amplifier with an active input balun

This paper presents a CMOS single-ended power amplifier with an active input balun for highly integrated UHF transmitter. Compared to the conventional balanced or differential power amplifiers with a passive output balun or transformer, this concept provides more compact circuit and takes smaller chip area. In addition, a gain of the active balun can be used to ease the system budget design. The designed single-ended two-stage power amplifier integrated circuit and an active input balun are fabricated using a 0.13 μm CMOS process with sizes of as small as 300X220 μm² and 110×110 μm², respectively. The overall circuits' performances are an output P1dB of 17.1 dBm, a high gain of 40 dB, and an OIP3 of 26.3 dBm with a power consumption of 210.3 mW.