Optimization design of wideband asymmetric Doherty power amplifiers with different LDMOS devices

In this paper, a wideband asymmetric Doherty power amplifier (WADPA), which has different LDMOS devices for the carrier and the peaking power amplifiers(MRF7S19080 and MRF8S19140), is designed with the stepped impedance transformer. The carrier and peaking amplifiers of the proposed Doherty amplifier operates in class-AB (2.76V) and class-C (1.3V) bias conditions, respectively, with a drain voltage of 27 V. By the help of the computer optimum design, the maximum PAE of 65.407% and the maximum output power of 54.953dBm at 1960MHz are obtained. At about 8dB back-off point, the PAE reaches 55.245%. When Pout equals to 47dBm, the wideband asymmetric Doherty power amplifier covers a bandwidth of 180MHz ranging from 1.87GHz to 2.05GHz while the gain flatness is between -0.3dB to 0.3dB, and the PAE of the whole band is more than 50%.