Grounded coplanar waveguide defected ground structure enabled mulitlayered passive circuits.

摘要

Passive circuits are essential to microwave and millimeter-wave (mm-wave) frequency design, especially as new commercial applications emerge for complementary metal-oxide semiconductor (CMOS) integrated circuits. However, it is challenging to design distributed passive circuits for CMOS due to the substrate loss and thin dielectric layers of the back-end-of-line (BEOL). Furthermore, distributed passive circuits need to be adapted for compactness and integration while overcoming these challenges and maintaining high performance. Grounded coplanar waveguide defected ground structures meet this need for compact and integrable passive circuits by utilizing the top and bottom ground planes of the transmission line to implement circuit elements. Defected ground structures (DGS) are distributed elements realized by etching specific patterns into the ground planes of transmission lines. These structures can be used in conjunction with the center conductor of planar transmission lines to reduce circuit size and/or improve performance. By implementing DGS in grounded coplanar waveguide (GCPW) multiple resonances and higher impedances can be achieved.;The resonant-based GCPW DGS are more compact than their microstrip and CPW counterparts and fit well into the vertical technology of back-end-of-line CMOS. This research demonstrates up to 80% size reduction at 5.8GHz by realizing spiral-shaped DGS in GCPW and applying the resulting GCPW DGS unit cell to a dual-behavior band-pass filter. The filter has been scaled to 60GHz and realized in a 130nm CMOS process by using floating metal strips to reduce the impact of the lossy silicon substrate. The impedance-based GCPW DGS, called EG-GCPW, have up to a 20:1 impedance ratio on Rogers RT/Duroid® 5880 and an impedance ratio of 15:1 on a benzocyclobutene post-CMOS process. These high impedance ratios increased the power division ratio of an unequal Wilkinson power divider to 7:1 and reduced the size of a stepped impedance low-pass filter by 30% at 2GHz. By using a dielectric isolation layer, the EG-GCPW was implemented in a silicon-based post-CMOS process demonstrating a 6:1 unequal Wilkinson power divider. Thus, GCPW DGS-enabled circuits show improved performance and reduced size of microwave and mm-wave passive circuits.