70% Efficient Dual-Input Doherty-Outphasing Power Amplifier for Large PAPR Signals

This paper presents the analysis, design and measured performance of a harmonically-tuned dual-input Doherty-outphasing power amplifier (DOPA) that can maintain high efficiency operation over a large dynamic range of output power. The load impedance trajectory presented to each device used in the DOPA is analyzed such that Doherty behavior at small output power levels seamlessly connects to outphasing operation at large output power levels. CW measurements will show a drain efficiency of 74% and 61% at 10 dB and 15 dB back-off respectively with a maximum output power of 51.2 dBm. A modulated drain efficiency of 70.2% was measured at 40.8 dBm output power using a 10 MHz LTE signal. Measured ACLR performance is better than -47.7 dBc, which is acceptable for practical use.