Multistage broadband amplifiers based on GaN HEMT technology for 3G/4G base station applications with extremely high bandwidth

GaN HFETs have been proposed for high power high linearity and high bandwidth applications and reached tremendous output power levels (T. Kikkawa et al., 2004). However, there are relatively few circuit examples especially for wideband power amplifiers fulfilling the requirements of future multiband/multistandard capable 3G/4G base stations. This work presents first promising results of realised GaN based wideband power amplifier demonstrators for the mentioned field of application. Two different amplifier concepts for the final stage of a power amplifier module for medium range multiband base station applications in the L- and S-band have been implemented as first amplifier demonstrators. The amplifiers have been characterized by using single carrier W-CDMA signals and showed a promising high bandwidth for output power levels up to > 10 W while meeting the 3GPP ACLR specification in a wide frequency range.