Concurrent Multiband Digital Outphasing Transmitter Architecture Using Multidimensional Power Coding

All-digital outphasing transmitter architecture using multidimensional power coding (MDPC) is proposed for non-contiguous concurrent multiband transmission with a high power efficiency. MDPC transforms multiband digital baseband signals into multi-bit low-resolution digital signals that drive switching-mode PAs. A prototype digital outphasing transmitter consists of two 1-GHz bandwidth GaN Class-D PAs and a Chireix power combiner. The two GaN PAs are driven by bipolar RF PWM signals, which are transformed from a concurrent dual-band LTE signal by MDPC. The dual-band LTE signal with 15-MHz aggregate channel bandwidth at 240 MHz and 500 MHz frequency band is transmitted with-30 dBc and-37 dBc out-of-band emissions, respectively. Digital outphasing achieves more than two times higher coding efficiency than conventional concurrent dual-band digital transmitters with the same PAs in Class-S operation. Measured power coding efficiencies of 35.4 % and 47.1 % are observed with outphasing bipolar and 3-level RF PWM signals respectively, which are encoded from the dual-band LTE signal