Abstract: In order to solve the problem that the traditional reflective predistortion circuit has low adjustability and little improvement on the Adjacent Channel Leakage Ratio (ACLR) of the power amplifier, this paper proposes a reflective adjustable analog predistortion circuit based on Schottky diodes. The circuit consists of 90 ° bridge, Schottky diode and bias circuit. Each branch uses two parallel Schottky diodes to generate nonlinear signals to offset the nonlinear distortion of the power amplifier. Each Schottky diode is an independent bias circuit, which can increase the degree of freedom of circuit regulation. By changing the bias of each Schottky diode, the amplitude and phase compensation of a larger dynamic range can be achieved. The S-band analog predistortion circuit based on this principle is used to linearize the Doherty power amplifier with a center frequency of 3. 5 GHz. The experimental results show that the ACLR of the measured power amplifier is improved by more than 14. 6 dBc when the output power is -28 dBm.