A fully digital polar transmitter using a digital-to-time converter for high data rate system

Digital polar transmitter is suitable for high integrated and power efficient implementation. In order to support high data rate communication systems, the digital polar transmitter need a high performance phase modulator with high resolution and sub-nanoseconds settling time. In this paper, as a phase modulator, a digital-to-time converter (DTC) with high resolution and short settling time is proposed. The DTC adopts serial delay architecture, and can be used in high data-rate and gigahertz wireless communication system. It exploits inverters with different delays to generate small phase differences while maintaining the sub-nanoseconds settling time. The DTC implemented in the TSMC 0.18 um CMOS process achieves the phase resolution of 0.78 ps and relative settling time of 0.7 ns with 2.5 GHz clock while consuming 0.8 mW of power.