An analog predistortion linearizer with independently tunable gain and adjustable shape using an asymmetric reflective structure

This paper presents a novel reflective analog predistortion (RAPD) linearizer with independently tunable gain conversion and tunable shape. Based on an asymmetric reflective topology consisting of a nonlinear branch and a linear branch, this linearizer achieves a simple circuit structure. Independent tuning of gain conversion of this linearizer is realized by changing the bias voltage of the linear branch. Meanwhile, the shape of the amplitude compensation of the linearizer can be adjusted by changing the bias voltage of the nonlinear impedance matching network (NIMN) in the nonlinear branch. The theoretical analysis and tuning process of this linearizer are discussed in detail. The tunability of the APD is verified by simulation and measurement results, which are in agreement. Furthermore, a Ku-band 50 W solid state power amplifier (SSPA) is linearized by the APD. The third-order intermodulation (C/IM3) is greater than 26.1 dBc at 2 dB output power backoff (OPBO) over the operating band of 10.7–12.7 GHz.