SRK 2024

POVZETEK
Širokopasovni RF-oddajniki morajo delovati v linearnem področju, da lahko ojačijo signal v nepopačeni obliki. Če oddajnik prekrmilimo, se pokvari spektralna maska, razmerje signal - šum in popačenje se zmanjša in komunikacija degradira ali se celo prekine. Vendar pa lahko do določene mere oddajnik vzbujamo s predpopačenim signalom in tako dobimo večjo moč in večji izkoristek. Prispevek govori o digitalnem predpopačenju signala v širokopasovnem E-band oddajniku. Pokažemo možne tehnike predpopačenj, njihove prednosti in slabosti, ter omejitve zaradi velike pasovne širine in potrebne procesne moči. Prikazani so matematični modeli, izpeljani iz Volterrovih serij. Predstavljeni so merilni rezultati digitalnega predpopačanja brez povratne zanke, ki je bilo realizirano na E-band linku.

ABSTRACT
Broadband RF transmitters must operate in a linear range to amplify the signal without distortion. If the transmitter is overdriven, the spectral mask is compromised, the signal-to-noise-and-distortion ratio decreases, and communication degrades or may even be interrupted. However, to some extent, the transmitter can be driven with a pre-distorted signal to achieve greater power and efficiency. This contribution discusses digital signal pre-distortion in a broadband E-band transmitter. We demonstrate possible pre-distortion techniques, their advantages and disadvantages, and limitations due to the large bandwidth and required processing power. Mathematical models derived from Volterra series are presented. Measurement results of digital pre-distortion without feedback loop, implemented on a E-band link, are also introduced.