A 0.05 cc Power Amplifier Module with a Novel Low Impedance Matching Technique for 900 MHz Personal Digital Cellular Phone

A 0.05 cc power amplifier module with a novel low impedance matching technique has been successfully developed for personal digital cellular (PDC) phones in Japan. Using this technique, a low pass network in an output matching circuit of the module has been eliminated thus improving the efficiency of the module. This elimination reduces the power loss of the output matching circuit by 0.2dB, which corresponds to a total current reduction of 20 mA and a power-added efficiency (PAE) enhancement of 3 %, in comparison with a conventional power amplifier module. In this technique, the load resistance of the module and input impedance of an isolator is 10 Ω, not 50 Ω. The PAE of the module corresponds to 61.7%, which is the highest PAE for PDC modules at the volume of 0.05 cc. The low impedance matching technique can be widely applied to various power amplifiers such as W-CDMA and N-CDMA, which are used with the isolator.