An Ultra-Broadband Load-Insensitive Dual-Input Doherty Power Amplifier MMIC Using Configurable Supply Voltage for 5G Smartphones

This article presents an ultra-broadband load-insensitive Doherty power amplifier (DPA) MMIC for fifth-generation (5G) smartphones to mitigate performance loss due to hand effects and mutual coupling effects. By adjusting supply voltages and input settings, we reconfigure the optimal output impedance of main and auxiliary PAs, and further preserve the back-off (BO) output power ( ${P}_{\text {BO}}$ ), saturated output power ( ${P}_{\max }$ ), as well as power-added efficiency ( $\text {PA}{{E}_{\text {BO}}}$ and $\text {PA}{{E}_{\max }}$ ). More importantly, this mismatch compensation theory is then expanded and validated in broadband DPA MMIC designs. As a proof of concept, a broadband load-insensitive dual-input DPA MMIC is fabricated using SANAN 250-nm GaAs HBT process. The prototype demonstrates cutting-edge performance, achieving 39%–44.5% $\text {PA}{{E}_{\max }}$ at ${P}_{\max }$ ranging from 34.2 to 35.1 dBm, and 35%–39% $\text {PA}{{E}_{\text {BO}}}$ at a 6-dB output BO (OBO) level in 1.7–2.7 GHz. Additionally, the proposed DPA MMIC showcases remarkable mismatch resilience over a full-span 2.5:1 voltage standing wave ratio (VSWR) circle. Specifically, the compensated $\text {PA}{{E}_{\max }}$ ranges from 31.5% to 43%, corresponding to ${P}_{\max }$ between 33 and 34.4 dBm, while at the 6-dB OBO power level, $\text {PA}{{E}_{\text {BO}}}$ is within the range of 30%–38% in 1.7–2.7 GHz. Moreover, when driven by a 100-MHz single-carrier 64-quadratic-amplitude modulation (QAM) signal with 6.5-dB peak-to average power ratio (PAPR), at a 50- $\Omega $ load, the DPA achieves an adjacent channel leakage ratio (ACLR) less than −26.4 dBc and an rms error vector magnitude (EVM) of −26/−25 dB for 1.7–2.7 GHz. Under a full-span 2.5:1 VSWR, the average output power and average PAE are measured at 26.5–27.9 dBm and 26.5%–35%, respectively, with an EVM below −22 dB and an ACLR less than −25.5 dB.