Tunable transmission lines for on-chip tuning and RF phase shifting front ends

This talk presents tunable transmission line structures suitable for implementation in Silicon along with some of their recent applications. First, the concept of a tunable t-line is introduced and some early examples with tunable line capacitance are reviewed. A tunable t-line structure in which both line inductance and capacitance is then presented along with its key advantages. Two implementations, one in CMOS operating at V-band frequencies and another one in SiGe BiCMOS optimized for Ka-band frequencies are presented in detail along with measurements and modeling considerations. Application examples of these tunable t-lines are discussed including an integrated 60GHz CMOS LNA with tunable frequency response and a 28GHz phased array with state-of-the-art beamforming performance.