A Novel High‐Power Analog Predistortion Structure Based on a Single Linearizing Branch

ABSTRACT This paper presents a novel analog predistortion (APD) design based on a single linearizing branch. The APD architecture design consists of a branch line coupler connected to a T‐junction and a single linearizing branch with a single PIN diode. The analytical equations for gain and phase conversions of the proposed APD structure are derived using even‐ and odd‐mode analysis. The design procedure of the proposed APD to compensate power amplifiers (PAs) for certain AM/AM and AM/PM is presented. Simulation and measurement results verify the performance of the proposed APD. The measurement results of the proposed APD achieve a 5.3‐dB conversion gain and 10° phase compression centered at 1 GHz with 9% fractional bandwidth. To our knowledge, this is the first matched reflective‐type APD that utilizes a single linearizing branch to simplify, compact, and reduce the power consumption of the APD structure. Furthermore, a 500‐W PA is linearized using the proposed APD. The measurements indicate that the APD shifts the 1‐dB compression point by 3.8 dB, and the phase change is reduced to less than 1.8°, whereas the IM3 is improved by 12 dB at 3‐dB output power backoff.