Linear Doherty power amplifier design based on adaptive input signal power control

In modern wireless communication systems, the trade-off between efficiency and linearity in Doherty power amplifiers (DPAs) remains a critical challenge. To address this, a novel Schottky diode-based input matching network is presented for peaking power amplifiers (PAs) which leverages a dual optimization mechanism: (1) adaptive gate DC bias adjustment via Schottky rectification, enabling Class B operation in high-power regions to enhance DPA linearity; and (2) nonlinear impedance modulation to suppress premature peaking PA activation in low-power regions, thereby improving back-off efficiency. Based on this structure, an asymmetric DPA is designed and manufactured, with continuous wave test results showing that saturation efficiency is higher than 50%, saturated output power reaches more than 43.4 dBm, and the back-off efficiency of 9 dB is 41.2%–55.6% in the operating band of 0.75–1.25 GHz. The adjacent channel power ratio (ACPR) of the PA is tested using a 20 MHz quadrature amplitude modulation (QAM) signal with a PAPR of 9 dB, and the test results show that, in the band of 1.0–1.3 GHz, the ACPR is −38.1 to −34.0 dBc and average efficiency is from 34.2%–45.5% at an average output power of 36 dBm, which verifies that the designed DPA has good linearity performance.