A novel mixed-mode LINC architecture for efficiency enhancement

This paper proposes a new architecture for linear amplification with nonlinear components (LINC) to achieve high efficiency enhancement. The proposed scheme, mixed-mode LINC, operates with two modes depending on an input signal level. It operates as a conventional LINC for a low input level and performs as the mixed-mode LINC, consisting of the conventional LINC system and an auxiliary amplifier, for a high input level. The system is verified with a WCDMA signal at 830 MHz. Using the mixed-mode LINC architecture, we achieved drain efficiency of 68% with a CW signal and 41% with the modulated signal, including -37 dBc and -47 dBc adjacent channel power ratio at 5 MHz and 10 MHz frequency offsets, respectively.