A Linearity Enhanced Power Recycling Pulse-Modulated Polar Transmitter Using Aliasing-Free Digital Pulsewidth Modulation

In this paper, a pulse-modulated power-recycling polar transmitter with dual-phase aliasing-free digital pulsewidth modulation (DPWM) for 4G long term evolution (LTE) is presented. This implementation is capable of achieving high linearity and efficiency by using concurrent power recycling and dual-phase aliasing-free DPWM. A prototype transmitter system is constructed with commercially available components. Measurements using a 16-QAM 20-MHz bandwidth LTE signal at 836.5 MHz achieved 41.2% drain efficiency at 23.8 dBm output power level while passing adjacent channel leakage ratio requirements without using digital pre-distortion. Compared to conventional DPWM, the aliasing-free DPWM signal provides a more linear output.