Predistortion Linearizer Design for Ku Band RF Power Amplifier

Abstract

This paper presents a $K_{u}$ band analog predistorter linearizer for improving the linearity of high-power radio frequency (RF) amplifiers. This method is applicable for both solid-state power amplifiers (SSPA) and traveling-wave tube amplifiers (TWTA). The designed linearizer consists of analog components, hence it is wideband as compared to the digital predistortion. Moreover, due to most of the passive components, the circuit is simpler and with the advantage of individual control of amplitude modulation to amplitude modulation (AM-AM) and amplitude modulation to phase modulation (AM-PM) conversions. For proof of concept, the designed linearizer is simulated with ZX60- $\pmb{14012}\mathbf{L}+\mathbf{ class}$ AB SSPA. The S2D SSPA model is extracted using vector network analyzer. The proposed linearizer shows a reduction in third order intermodulation of 37 dB approximately at 4 dB output power backoff for two-tone signal. Similarly, for Long-Term Evolution (LTE) 20 MHz signal after linearization adjacent channel power ratio is approximately 47 dBc and shows a correction of 16 dB.