Comments on Novel Dual-Band Matching Network for Effective Design of Concurrent Dual-Band Power Amplifiers

A novel dual-band matching network for concurrent dual-band power amplifiers has been proposed and discussed by Fu et al. in January 2014. The first stage matching network effectively accomplished real-to-complex impedance transformation by utilizing a transmission line, a short-circuited stub and an open-circuited stub. However, the obtainment of the values of the electrical parameters are realized by tuning and observing Smith Chart, no analytical design methodology given. In this comment, rigorous design equations of the real-to-complex matching network are extracted, and two numerical instances are demonstrated for verification. Additionally, an error about the input impedance in original paper is corrected.