Design of L and X Band Class E Power Amplifiers with GaAs pHEMT Technology for Space SAR

The paper describes the design of class E power amplifiers for SAR space applications, exploiting a 0.35-um pHEMT GaAs process. An L-band 10-Watt push-pull hybrid amplifier has been designed and implemented. The HPA features 73% PAE and 81% drain efficiency at 1.275 GHz. The performances of the class E HPA are also compared with a class AB HPA, exploiting the same technology. Class E design was also evaluated at X band, which for this technology is beyond the limit for the devices' class E operation capability. Two different prototype amplifiers were designed exploiting different device periphery. The single-cell amplifier delivers about 31 dBm output power with 64% peak PAE, whereas the double-cell circuit features 27 dBm output power with 70% peak PAE. These prototype amplifiers prove the possibility to use this process for the design of X band MMIC HPA for SAR space applications operating with high efficiency.