Achieving frequency-agile radio

This paper describes techniques to achieve high bandwidth systems for a frequency-agile radio. A bottom-up approach has been followed where the tunability and bandwidth of the basic building blocks are enhanced, and then these improved elements are introduced into higher-level blocks in order to achieve large bandwidths. The approach has been used to improve the tunability and bandwidth of an active inductor by enhancing the tuning range of a tunable active resistor. This highly tunable active inductor is then used in a VCO that achieves more than 100% of frequency tuning range. All circuits have been fabricated in 0.18 /spl mu/m SiGe BiCMOS process.