WebLab: A Web-Based Setup for PA Digital Predistortion and Characterization [Application Notes]

The WebLab that is described here was initially motivated by the 2014 IEEE Microwave Theory and Techniques Society International Microwave Symposium\´s (IMS2014\´s) Student Design Competition on Digital Predistortion (DPD) Linearization, described in "Accurate Linearization with Low-Complexity Models Using Cascaded Digital Predistortion Systems," by Barradas et. al on page 94 in this issue of IEEE Microwave Magazine. To make a comparison of DPD algorithm performance, it is necessary to have one device under test (DUT), a Doherty power amplifier (PA), and one measurement setup for everybody to use. This was not a problem for the finals of the competition because the competitors would all be physically present at the same location. However, for the preparations starting half a year in advance, this posed a serious problem. The solution we implemented takes advantage of the fact that most universities today provide a decent Internet connection for their employees and students. A remotely accessible WebLab seemed to be a viable solution to the problem of letting the competitors practice on the actual DUT using the same measurement setup before the final competition at IMS2014. We decided to construct a Web-based remote-controlled PA measurement setup that allowed any user (not only the competitors) to upload his or her own input data and download the resulting measured output data. The Web page and instructions for using it can be found at http://dpdcompetition.com.