The Ping-Pong Tunable Delay Line In A Super-Resilient Delay-Locked Loop

The Tunable Delay Line ( TDL) is the most important building block in a modern cell-based timing circuit such as Phase-Locked Loop ( PLL) or Delay-Locked Loop ( DLL). In previously proposed TDLs, one dilemma exists - they cannot be both power efficient and environmentally adaptive at the same time. In this paper, we present an effective solution for such a dilemma - a novel "ping-pong delay line" architecture. The idea is to use two small cell-based delay lines operated in a synergistic manner in the sense that they exchange the "role of command" dynamically like in a ping-pong game, and thereby jointly reacting to severe environmental changes over a very wide range. This proposed ping-pong delay line has been incorporated in a Delay-Locked Loop ( DLL) design, to demonstrate its advantages by post-layout simulation.