A GCPW slow-wave transmission line with improved wavelength reduction technique by adopting capacitor array

Abstract

This letter presents a grounded coplanar waveguide (GCPW) slow-wave transmission line (SWTL) with an improved wavelength reduction technique by adopting capacitor array. By cross-interleaving additional capacitors between a signal line and side ground planes, the total capacitance in the capacitor array increases approximately two times compared to the conventional structure, allowing designers to choose a smaller signal conductor's width for higher inductance, thus, improving wavelength reduction performance while preserving the same characteristic impedance. At the 150 GHz frequency of interest, the proposed GCPW SWTL shows approximately 20% and 62.16% reduction in wavelength compared to the reported GCPW SWTL and regular CPW, respectively, with the same 35 Omega $35\,{\rm{\Omega }}$ characteristic impedance. To prove the effectiveness of the proposed SWTL concept, the proposed GCPW SWTL test patterns are fabricated in a 65 nm CMOS process.