Co-design of Matching Sub-networks to Realize Broadband Symmetrical Doherty with Configurable Back-off Region

In this brief, a technique using the co-design of three matching sub-networks is proposed to solve the contradiction between bandwidth and extended the back-off region of symmetrical Doherty power amplifier (DPA). The phase-shifting solution space of DPA output matching networks is calculated, and its relationship with the input impedance of the post-matching network is analyzed with and without the frequency variable. Configurable back-off region and adjustable operating center frequency can also be realized in the design by using the proposed method. The design flow is given, and then a detailed example under 9-dB back-off region is presented. To verify the proposed theory, a DPA is designed and fabricated across 1.9-2.4 GHz. The experimental results show drain efficiencies of 44.2-49.7% at 8.5-9 dB output power back-off levels across 1.9-2.4 GHz. The fabricated DPA achieves output powers of 44.1-44.8 dBm.