A fully integrated 26 dBm linearized RF power amplifier in 65nm CMOS technology

In this paper, design and measurements of a fully integrated power amplifier (PA) are presented. The PA consists of two amplifying chains each having a driver and a power stage. A low loss on chip power combiner combines the outputs from two amplifying chains, and also performs impedance transformation and differential to single-ended conversion. To linearize the PA, the driver stage is biased in class-C, acting as a pre-distorter for the power stage which is biased in class-AB. The linearization scheme is validated by measurements, improving the third order intermodulation distortion (IMD3) by 7dB, output referred 1-dB compression point by 4dB, and adjacent channel leakage ratio (ACLR) by 4.5 dB. With a supply voltage of 2.2V, the PA delivers a saturated output power of 26.1 dBm with a power added efficiency (PAE) of 26.8% at operating frequency of 2.24 GHz. The measured power gain of the PA is 21.8 dB, and the output referred 1-dB compression point is 25.4 dBm. The ACLR1 (5 MHz offset) is better than -33 dBc while transmitting a 23dBm WCDMA signal. The circuit is manufactured in a standard 65nm CMOS process and occupies 1mm² of chip area.