Design and Development of Ku-Band STALO for low phase noise applications

Radar systems have largely adopted STALO local-oscillator (LO) generator for up/down conversions in TR modules. This paper describes an overview of Ku band Stable LO generation for the Transmitter and Receiver system with Low phase noise application. The LO chain Generates 15.375 GHz signal for up/down conversion. So, here the highly stable OCXO of 125 MHz is used as a reference signal to derive LO (Ku-band) signal and it is synthesized using LMX2615 Frequency synthesizer with OCXO frequency as a Reference clock signal followed by Frequency doubler for Upconversion of the LMX2615 output frequency. In the process of generation of LO chain, microstrip filters have been used that is the coupled line filter because of their good coupling gap and also wiggy coupler has been used for better isolation and directivity response which has been designed. The system typically needs LO with a specification of 0.5 dbm, low phase noise of -80 dBc/Hz @ 100 Hz offset, LO spurious, and harmonic rejection of <-60 dBc.