The EFR32MG12 contains a high performance, low phase noise, fully integrated fractional-N frequency synthesizer. The synthesizer isused in receive mode to generate the LO frequency used by the down-conversion mixer. It is also used in transmit mode to directlygenerate the modulated RF carrier.The fractional-N architecture provides excellent phase noise performance combined with frequency resolution better than 100 Hz, withlow energy consumption. The synthesizer has fast frequency settling which allows very short receiver and transmitter wake up times tooptimize system energy consumption.