Getting ready for beyond-5G, super-IoT and 6G at hardware passive components level: a multi-state RF-MEMS monolithic step attenuator analyzed up to 60 GHz

Looking at 2030, the landscape of technology will be dominated by paradigms like 6G, Super-IoT (Internet of Things) and Tactile Internet (TI). From the perspective of Hardware (HW) components technologies, the turning into reality of such scenarios will demand for a radical reconceptualization of devices, sub-systems and systems, probably modifying the concept of HW itself. Driven by the target of taking initial steps in the direction of such future applications, this work discusses a 4 bit RF power step attenuator entirely realized in RF-MEMS technology. Physical samples are fabricated in a surface micromachining technology and rely on electrostatically actuated cantilevered MEMS ohmic switches to select or short resistive loads placed along the RF line. Fabricated devices are tested and validated up to 30 GHz, while simulations are discussed up to 60 GHz for the full set of allowed configurations. Despite a few technology non-idealities, the network shows levels of attenuation with a flatness as good as 1 dB over 60 GHz frequency span. The measured and simulated data reported in this work offer important indications on how to improve the network concept, both at technology and design level.