Study On The Techniques For Dual-Band High Efficiency RF Power Amplifiers

The 3G system and 2G system's made every mobile operator operate several different systems. Thus, there were more power amplifiers worked would greatly increase the power consumption as well as the volume of the base station. Therefore, a dual-band high efficiency RF power amplifier could not only save the electricity for the operators, but also could help the operators to save the construction costs of base stations, including reducing amplifier's power and cooling equipments, reducing the base volume. This paper proposed the dual-band frequency characteristics of the composite right/left-handed transmission line combined with the Doherty structure. These would not only make power amplifier work in the dual-band, but also improved the power amplifier's efficiency when the power was back.This thesis included the following three parts:The first part focused on the principle of Doherty amplifier and composite right/left-handed transmission line (CRLH-TL).The second part was concerned about the Doherty PA for the 460MHz band and the test on the prototype. Firstly, it used MRF9045 which was one of the Freescale's PA chips, to design a driver amplifier. The test results showed that the driver PA had 24dB gain, the output power of 1dB compression point was 45.1dBm, and the maximum added efficiency reached 62.2%. Secondly, it designed a Doherty PA for on the 460MHz band using the Freescale's PA MRF9060. It proposed that used a microstrip line and a shunt capacitor instead of the quarter of microstrip line of the Doherty output, could reduce the size of the PA. The prototype test results showed that the added efficiency of the Doherty PA attained 56.402%, and the maximum output power obtained 46.78dBm.The third part proposed to use the composite right/left-handed transmission line combined with the Doherty structure to design a double-band high efficiency RF PA. The optimization results showed that for both 920MHz and 1900MHz bands, the dual-band Doherty amplifier's added efficiency was nearly higher of 11% than that of the dual-band Class AB amplifier. Especially at the 6dB power back of the 920MHz and 1900MHz bands, the Doherty amplifier's PAE compared with the class AB amplifier's increased 14.946% and 26.825%, respectively.