An 11 GS/s 2×10b 20–26 GHz Modulator using Segmented Non-Linear RF-DACs and Non-Overlapping LO signals

Abstract

We present a Cartesian I/Q modulator based on dual 10-bit RF-DACs. Non-overlapping LO signals and a segmented RF - DAC architecture with scaled bit currents contribute to good linearity and allow low-complexity DPD. Unit-cell flip-flops with a balanced clock distribution enable a high sample rate. Drive slope control for data switches reduce out-of-band emissions. Implemented in 22 nm FDSOI CMOS, the modulator operates up to 26 GHz with a maximum sample rate of 11 GS/s. The modulator is used to demonstrate transmission of a 64QAM signal at 13.2 Gb/s, a 256QAM signal at 7.33 Gb/s, and an OFDM signal comprising four aggregated 400-MHz 64QAM channels at an EVM of 6.43 %. The results demonstrate the potential of the proposed modulator architecture for realization of ultra wideband transmitters for high performance mm-wave systems.