A Reconfigurable Analog Predistorter Using Tunable Impendence Matching Network

Abstract A reconfigurable analog predistoter (APD) based on tunable impedance matching network (TIMN) is proposed in this brief. Firstly, a design method to specific gain and phase conversions is introduced. The equivalent circuit parameters of the impedance matching network (IMN) can be computed for the desired gain and phase conversions. To simplify the design, these parameters can be transformed to the terminal impedance of the IMN. Then the complicated nonlinear circuits design can be transformed to the IMN design. Secondly, a reconfigurable APD using the proposed method is presented for high tuning capability. By designing the coverage area of the TIMN, an experimental reconfigurable APD for traveling-wave tube amplifiers (TWTAs) & solid-state power amplifiers (SSPAs) is designed and fabricated. The fabricated APD shows more than 21 dB tuning range of gain conversion and 114° tuning range of phase conversion in 5.7-6.3 GHz. Good linearity improvement has been obtained for a 45 W C-band TWTA and a 5 W SSPA only by changing the APD bias voltage.