Metamaterial artificial transmission line structures in CMOS for tunable insertion phase at 30 GHz

Three CMOS integrated circuits are presented that utilize metamaterial composite right/left handed (CRLH) transmission lines (TLs) for tunable zero insertion phase at 30 GHz. Initially, two passive fixed TL structures are realized followed by an active design using accumulation-mode NMOS varactors. An tunable insertion from -9deg to +27deg can be observed. Results suggest the possibility of zero, advanced or delayed insertion phases by element variation or by the use of such simple active components. Simulation and measured results are in agreement with CRLH TL theory, and display a linear insertion phase and flat group delay values. These findings suggest that such high speed CRLH TLs structures can be implemented for active linear antenna array feeding networks and other high speed circuits in CMOS for millimeter wave frequencies of operation.