A Wideband Digital Polar Transmitter with Integrated Capacitor-DAC-Based Constant-Envelope Digital-to-Phase Converter

This paper presents a wideband digital polar transmitter (DPTX) with integrated capacitor-DAC-based constant-envelope digital-to-phase converter (DPC). The switched-capacitor DAC topology is adopted to improve the linearity. The harmonic rejection and cell-reused techniques are employed to reject the 3
^rd
/5
^th
-order harmonics and reduce the power consumption, respectively. The measurement results of DPC demonstrate the maximum INL and DNL of 1 and 0.8 degrees with the power consumption of 12.7mW@1.5GHz. The DPTX obtains the peak output power of 20.1dBm with 23.7% system efficiency and wideband frequency coverage over 1.2-2.5GHz with only 0.7dB power variation. When amplifying a 10MHz 64QAM LTE signal at 1.5GHz, it achieves -28.6dB EVM and 15.2% system efficiency at 15.0dBm average output power.