The ACS8946 JAM PLL is a Jitter-Attenuating, Multiplying differential Phase-Locked Loop, for generating low jitter output clocks compliant up to SONET OC-12 and STM-4 622.08 MHz specifications. Its primary function is to clean up clock jitter for high performance optical line cards with OC-12 framers and serializers. It also provides reference switching functionality for line card protection, and frequency translation.