Compacted Ka-Band CMOS Rat-Race Hybrid Using Synthesized Transmission Lines

This paper presents a compact Ka-band rat-race hybrid using synthesized transmission lines (TLs) so-called complementary-conducting strips transmission line (CCS-TL). The hybrid is realized by two-dimensional (2D) meandered CCS-TLs on silicon substrate with a thickness of 480 mum. The first-pass design was fabricated by using CMOS 0.18 mum 1P6M technology and characterized by performing on-wafer measurements. The experimental results, which show a good agreement with the theoretical data, demonstrate the viable approach of the on-chip CCS-TLs. The prototype has an isolation of 20 dB from 26.0 GHz to 36.0 GHz. The input reflection-loss of each port is lower than -15dB from 27.0 GHz to 39.0 GHz. The effective area of the prototype is 600 mum by 460 mum.