Integration of a cellular handset power amplifier and a DC/DC converter in a Silicon-On-Insulator (SOI) technology

A DC/DC buck converter was integrated with a cellular handset power amplifier (PA) in a silicon-on-insulator (SOI) technology. The technology was designed to allow integration of high-performance reliable RF power devices with the front-end. The power devices uses an LDMOS-based MOS device, called integrated power MOS (IPMOS). A 3-stage power amplifier was designed for GSM850/900 and DCS/PCS bands. The PA achieved typical power added efficiencies (PAE) greater than 60% with Pout ranging from 35.5 to 36.7 dBm at GSM850/900 MHz band, and it achieved typical PAEs in the range of 44 to 49 % with Pout ranging from 33.6 to 33.8 dBm at DCS/PCS band. The PAE was also measured when the DC/DC converter biased the PA. Up to 25-percentage-point improvement in the PAE was observed compared to the case where the output power was controlled by varying the input power. The spurious emissions in the transmit band and the receive band noise were also reported.