A highly efficient asymmetric Doherty Power Amplifier with a new output combining circuit

An asymmetric Doherty Power Amplifier (ADPA) is introduced using a new output combining circuit for easy of implementation with a large matching tolerance. The proposed APDA has been implemented using GaN HEMT devices at 2.6 GHz for WiMAX signal with 5MHz bandwidth and 8.3 dB peak to average power ratio. This ADPA delivers a saturated output power of 51.7 dBm and a drain efficiency of 60.4% at an average output power of 43.6 dBm. After linearization using digital feedback predistortion technique, the ADPA satisfies the linearity specification with -51.98 dBc of adjacent channel leakage ratio at 10MHz offset. To the best of our knowledge, the drain efficiency of 60.4% is the highest efficiency at 2.6GHz frequency for a WiMAX signal with 8.3dB PAPR.