Abstract—In this paper, we compare a shift register (SR) to a delay-locked loop (DLL) for flexible multiphase clock generation, and motivate why a SR is not only more flexible but often also better. For a given power budget, we show that a SR almost always generates less jitter than a DLL, assuming both are realized with current-mode logic. This is due to differences in jitter accumulation and the possibility to choose latch delays in a SR much smaller than the delays of DLL elements. For N-phase clock generation, a SR also functions as a divide-by-N and requires a voltage-controlled oscillator with N-times higher frequency. However, this does not necessary lead to more power consumption and can even have advantages like higher Q and less area for the inductors.
|Number of pages||5|
|Journal||IEEE transactions on circuits and systems II: express briefs|
|Publication status||Published - 1 Mar 2008|
Gao, X., Klumperink, E. A. M., & Nauta, B. (2008). Advantages of Shift Registers over DLLs for Flexible Low Jitter Multiphase Clock Generation. IEEE transactions on circuits and systems II: express briefs, 55(3), 244-248. [10.1109/TCSII.2008.918972]. https://doi.org/10.1109/TCSII.2008.918972