A Single-Supply Single-Core Inverse Class-D Digital Power Amplifier with Enhanced Power Back-Off Efficiency Adopting Output Power Scaling Technique

This work presents a current-mode inverse Class-D digital PA (DPA) with enhanced power back-off (PBO) efficiency. The PA adopts extra switches, which allows the scaling in the output voltage swing by half, leading to (theoretically) 6 dB enhancement in PBO efficiency while maintaining (ideally) 100% drain efficiency (DE). Implemented in a 65 nm CMOS, the proposed DPA shows the improvement in DE by ×1.5 at 4.2 dB PBO in comparison with normalized Class-B PA while requiring only one transformer and single-supply voltage.