A dual-phase pulse-modulated polar transmitter with high efficiency and linearity using power recycling

This paper presents a pulse-modulated power-recycling polar transmitter with a dual-phase digital pulsewidth modulation for the 4G long term evolution (LTE) system. This implementation is capable of achieving high linearity and efficiency by recycling the power of residual spurs from pulse modulation. A prototype balanced transmitter system is constructed with commercially available components. Measurements using a 16-QAM 10-MHz bandwidth LTE signal at 836.5 MHz, it achieves 17.3% efficiency improvement at 21-dBm output power level while passing the stringent adjacent channel leakage power ratio requirements without using any calibration or pre-distortion.