A Digitally Assisted Dual-Input Dual-Band Doherty Power Amplifier With Enhanced Efficiency and Linearity

This brief presents a dual-input dual-band Doherty power amplifier (DPA) that operates at 850 and 2100 MHz. The presented DPA utilizes a compact input matching network and composite right-left handed phase offset line. This DPA delivers a peak output power of around 44.5 dBm with an efficiency enhancement region upto 9-10 dB output power back off at both the operating frequencies. Further, the phase offset angles between main and auxiliary power amplifiers are controlled digitally at both the operating frequencies in order to improve the efficiency and linearity throughout the back-off region. As compared to the conventional phase offset of 90°, the optimum offset angle of 120° at 850 MHz provides an improvement of 13% in drain efficiency and 8.5 dB in C/IMD3. Similarly, an improvement of 4 dB in C/IMD3 is achieved by digitally setting a phase offset of 80° at 2100 MHz.