The SY89420V device consists of two identical, low jitter, digital Phase Locked Loops based on Micrel-Synergy's differential PLL technology. Each of the PLLs (PLLA and PLLB) is capable of operating in the 30MHz to 560MHz input reference frequency range independently of the other and is configurable separately. The PLLs can be configured to be matched in all regards, or can be configured so that PLLB is used as a frequency doubler, while PLLA is used to regenerate the undoubled frequency. Two reference inputs (RINX and RINX), two feedback inputs (FINX and FINX), two filter pins (F1X and F2X) and two differential outputs (FOUTX and FOUTX) are provided for each of the two PLLs. The reference and feedback inputs can be used as either differential or single-ended inputs. In single-ended mode RINX and FINX can be connected to either VBB for normal 100K PECL levels or VTH for normal TTL levels.