A pulse-mode CMOS power amplifier for multi-band LTE femtocell base stations

This paper presents a wide bandwidth fully integrated CMOS power amplifier (PA) suitable for pulse-mode operation. The CMOS PA was implemented in a 90-nm process with core size of 1 mm2. A pulse-modulated polar transmitter for LTE femtocell applications was constructed with this switching CMOS PA using the aliasing-free digital pulse-width modulation technique. With conventional memoryless digital predistortion, the polar transmitter achieved 23.5% efficiency and 19.5-dBm output power at 2.4 GHz. Moreover, the proposed transmitter can also pass the −45-dBc ACLR requirement over a wide frequency range from the first channel in downlink band-1 to the last channel in downlink band-7 for LTE home femtocell base stations.