Impact of All-Digital PLL on SoC Testing

This paper, as a case study and tutorial, discusses testing methods for general PLL features and their operating margin. These methods can be applied all for analog-, digital- and PW-PLLs. There are various kinds of on-chip measurement macros which can be applied for the PLL testing, and for the direction toward digitally assisted analog circuit testing, it is shown that a digitally controlled variable delay and a time to digital converter have a big possibility for PLL testing using only digital signals.