A 3.8 mW Sub-Sampling Direct RF-to-Digital Converter for Polar Receiver Achieving 1.94 Gb/s Data Rate with 1024-APSK Modulation

This paper presents a direct RF-to-digital converter (RDC) for polar RX. It consists of a pair of TDCs, an ADC, and a precise sampling position control system. Unlike conventional direct-RF sampling receivers, the RDC samples the input RF signal at baseband rate. It is capable of directly digitizing the phase and amplitude of the received modulated RF signals. It is compatible with a variety of modulations and has advantages of relaxed system requirements on phase noise and linearity when APSK is used. The RDC achieves a max rate of 1.94 GB/s with 1024-APSK at a carrier of 6 GHz, consuming only 3.8mW.