A digitally controlled power amplifier with neutralization capacitors for Zigbee™ applications

This paper presents a single chip CMOS power amplifier with neutralization capacitors for Zigbee system according to IEEE 802.15.4. A novel structure with digital interface is adopted, which allows the output power of a PA to be controlled by baseband signal directly, so there is no need for DAC. The neutralization capacitors will increase reverse isolation. The chip is implemented in SMIC 0.18 mu m CMOS technology. Measurement shows that the proposed power amplifier has a 13.5 dB power gain, 3.48 dBm output power and 35.1% PAE at P sub(1dB) point. The core area is 0.73 x 0.55 mm super(2).