Linearization of Ka-band high power amplifiers

Increased commercial use of satellite terminals, broadband wireless communications and high-data link has created a strong demand for Ka-band high power amplifiers (HPAs) coupled with high power efficiency and good linearity performance. To meet the stringent linearity requirement without largely sacrificing output power and efficiency, linearization is the only solution. This paper demonstrates the effectiveness of digital predistortion (DPD) in linearization of Ka-band HPAs by presenting the experimental results from our memory polynomial predistorter based wideband DPD testbed. Tested on an in-house developed 15W Ka-band solid state power amplifier (SSPA), it is shown that with linearization 15-25 dB linearity improvement is achieved for 64-QAM and 8-tone signals. While meeting the required linearity, this will lead to an significant increase on the output power and efficiency, compared to the conventional back-off method.