Abstract: Background: Nowadays delay locked loops have a very wide range of applications in integrated circuits such as clock recovery circuits, microprocessors, memory circuits, frequency multipliers and synthesizers. Delay locked loops like Phase Locked Loops, mainly aim to synchronize the clock, nevertheless they have a lot of other advantages like high lock speed, unconditional stability, better jitter performance, and lower occupied area with respect to phase locked loops. Methods: In this paper, we evaluate nine structures of analog delay locked loops with wide frequency range, and discuss their embedded techniques to increase and improve frequency range. In this regard, we describe designed blocks like charge pump, voltage controlled delay line, phase detector and start controller circuit. Conclusion: In these structures, in addition to frequency range increase, other parameters like consumption power, jitter, lock time, simplicity and complexity of them are also considered.
