Digital predistortion of a Doherty amplifier with a weak memory within a connected solution

Digital predistortion has been shown to effectively address the growing demand for highly linear and more power efficient amplifiers in base stations. Doherty amplifiers have demonstrated greater efficiency than traditional amplifiers but with a high adjacent channel power ratio. This paper describes a digital predistortion implementation within the ADS Ptolemy environment and a connected solution consisting of an electronic signal generator (ESG), power amplifier (PA), and vector signal analyzer (VSA). The connected solution enables the evaluation of a PA's performance with the addition of digital predistortion. A 30 W Doherty amplifier with a weak memory was evaluated within the connected solution. Two WCDMA carriers were applied to our system, and the results show 15 dB reduction at 5 MHz offset and 12 dB reduction at -5 MHz offset.