High Dynamic Range Attenuator Using ScDDAs as Integrated Distributed Tunable Resistors on Silicon

This letter presents an all-integrated reflection attenuator at 10 GHz with a high attenuation range and low off-state insertion loss using ScDDAs (Semiconductor Distributed Doped Areas) as tunable loads. The branch-line coupler topology used features a 20% bandwidth. The measured performance shows an attenuation range from 2 dB to 41 dB. With the use of integrated tunable loads into the silicon substrate, the presented device is competitive in die area, insertion loss and attenuation range while providing convenient DC biasing and straightforward frequency upscaling. The high integrability leads to perspectives of use in MMIC (Monolithic Microwave Integrated Circuit) systems at higher frequencies. Further work is presented showing improvements in ScDDA models using highly coupled semiconductor physics and electromagnetic structure co-simulation on COMSOL Multiphysics, replicating a high fidelity current-attenuation relationship by using a high resolution volumetric resistivity field instead of the previously used cuboid channel model, opening the way to high performance RF systems co designed on semiconductors.