Since 2002, IR-UWB has been proposed as the ultimate wireless technology for localization, and low-/moderate-data rate wireless applications. It is based on the transmission of very short duration pulses on the order of few nanosecond, and enable aggressive duty cycling at the transmitters and at thanks to ad-hoc techniques to recover transmitted clock, duty cycling at the receivers, ideally up to 0.1%. With such very limited time used to wirelessly transmit information compared to a symbol duration, its very low power spectral density, IR-UWB circuits and systems can be very flexible solutions for ultra-low-power internet of things wireless nodes, and ideally a variety of physical modulations and circuit-level techniques be used to achieve good performance without a significant complexity increase. The talk presents recent low complexity solutions for IoT radios suited to a wide class of application domains where moderate/low data rate and short communication distance is pursued.