Passive and active CMOS devices based on Slow-wave Transmission Lines (SW Tlines) have been developed since four years in the group. State-of-art results have been recently obtained, with Q factors greater than 45 at 60 GHz with a BiCMOS9MW technology from STMicroelectronics, high performance circuits like power dividers and filters, and also high-gain, high-linearity 60 GHz power Amplifiers in a CMOS 65 nm technology, where classical microstrip stubs were replaced by SW TLines for the matching network design.
New circuits are under development in either bulk CMOS 40 nm and 28 nm, or CMOS-SOI 65 nm technologies : wide bandwidth miniaturized baluns, multi-stage power Amplifiers, and filters. A new analytical model has also been developed recently for SW TLines, taking into account all the losses of the structure. It will be published soon.
Post-CMOS and beyond-CMOS technologies Researches are carried out toward the development of post-CMOS or beyond CMOS mmW tunable circuits to address the problem of millimetre-wave (mmW) beam-forming systems and future multi-standard or medium bandwidth telecommunication systems.
Post-CMOS process consists in an etching step without masking (after the CMOS process), carried out to release some metallic layers of the CMOS back-end, leading to MEMS structures. A new technology is under development with this approach, with the aim of developing high-performance (low-loss and small-size) mmW phase shifters.
Tunable filters are also under development with this technology.
Beyond CMOStechnologies consist in embedding some new materials which are not allowed yet in a standard CMOS or BiCMOS technology.
The BST is one of these possible materials. Some researches in the group are directed toward the development of tunable phase shifters and filters using such a technology. These materials being not developed at IMEP-LAHC, some collaborations have been recently initiated with LME-USP laboratory in Brasil in order to embed these materials into the new circuits designed by the RFM group. Passive circuits on porous silicon have also been developed with state-of-art performance in term of attenuation and achievable characteristic impedance, thanks to collaboration with IMEL laboratory in Greece.