Wideband True Time Delay Cells

Abstract

True-time delay (TTD) cells are used in timed array receivers for wideband multi-antenna topologies. TTD cells are divided into two major categories: silicon-based and non-silicon-based structures. Non-silicon-based structures have very good bandwidth but are bulky in the below 10 GHz frequency band. Silicon-based TTD cells are much more compact and better candidates for integrated circuit (IC) design. Passive and active approaches are the two ways to have a silicon-based TTD cell. Passive TTD cells are built by transmission lines (TL), artificial transmission lines (ATL), and LC ladder networks. Their power consumption is very low, and the delay bandwidth is good, but they are still bulky at low frequencies like below 5 GHz applications. Active all-pass filters as TTD cells are presented for these issues. In this chapter, we will discuss the challenges of inductor-based TTD cells. Then, inductor-less TTD cells are presented to address some of the previous structure’s issues. Finally, we will talk about these structures’ challenges as well. Then, the nonidealities effects on the TTD cell’s performance are investigated, and the body bias technique is presented to address these issues.