A High Performance Slow-Wave Microstrip Line on CMOS Process

A high performance slow-wave microstrip line (S-MSL) structure is presented in this letter based on a 90nm CMOS technology. The ground planes of the S-MSL are composed of metal strips of two different metal layers which are long and thin, arranged in zigzags. Some test structures with different geometries are designed and fabricated using an eight-metal 90nm CMOS process. On-wafer measurements show that the proposed S-MSL demonstrates a better performance when compared to conventional microstrip line (MSL) and slow-wave coplanar waveguide (S-CPW). For one of S-MSLs, high quality factor Q ranges from 5 to 25 between 10 and 40 GHz. High effective dielectric permittivity no less than 28 leads to a very high slow-wave factor and high miniaturization. The wavelength of the measured S-MSL is 1.4mm at 40 GHz, much shorter than the conventional microstrip.