Ro, Eng

Duplexers are circuits used in transmit/receive communication systems for separation of the different frequencies signal paths connected at the same antenna. In the case of satellite communications, the frequency band between 8 – 12 GHz (also known as “X band”) is mostly used. The circuits developed for these applications need to satisfy strict performance criteria, such as reduced size and weight and extreme environment operating capability.
In the frame of the project, monolithic integrated filter and duplexer circuits were developed on thin piezoelectric layers, based on surface acoustic wave resonators, with operating frequencies in the X band with interdigital transducers of 100-200 nm widths. Advanced modeling and design methods based on multiphysic simulations, 3D electromagnetic simulations and circuit level model parameter extraction were employed. The structures were fabricated using nanolithographic technologies and were measured with dedicated equipment.

This new class of circuits is compatible with monolithic integration with active and passive components fabricated on a III-group nitrides (Ga, Al, Sc) technological platform. The TRL-4 technological maturity level (“validation of the components and/or system in laboratory conditions”) opens new opportunities for 5G/6G technology applications.

(a)	(b)
(c)	(d)

Band pass filter monolithic integrated with surface acoustic wave resonators and central operating frequency of 8.06 GHz: (a) 3D electromagnetic model; (b) fabricated structure with total area of 0.75 × 2.9 mm2; (c) detail of the 130 nm interdigital transducers obtained with the scanning electron microscope (SEM); (d) experimental characterization [A.C. Bunea et al., EuMW 2022].