Implementation of RF narrow band frequency synthesizer for LoRaWAN system

Abstract

A narrowband frequency synthesizer has been designed and fabricated to generate two bands of 868MHz(Europe) and 915MHz(North America) with a same chip. It will be applied as the LoRaWAN system. Measurement results show that the frequency synthesizer has bandwidth of 1,670 ∼ 1,972MHz(about 16.57% center frequency ratio), and low phase noise characteristics of −83.74dBc/Hz at 50μA charge pump output current and −86.81dBc/Hz at 300μA charge pump output current on 100KHz offset.