Vipin Kumar | Jayasheela C S | Sivakumar R | Mahadev Sarkar | Shailendra Singh
INTRODUCTION
In recent times, electronic warfare and navigation technology have changed very rapidly. This change in technology requires highly precise and stable RF and microwave systems. Performance reliability of such systems is directly dependent on its ability to maintain its operational accuracy during dynamic vibration environment. Enough literature is available on phase locked loop (PLL) design and development techniques for frequency synthesis but its stabilization is a challenging task especially under random vibration environment of high g value. Degradation of phase noise of generated signal under random vibration is very crucial which limits the performance of such systems and their use in mild to severe dynamic environmental conditions. Phase noise of system is reliant on reference-induced phase-modulated (PM) noise which becomes excessively large at X-band and higher frequencies.
Reference source composed of piezoelectric material (acceleration sensitive devices) and its output signal purity is very sensitive to any type of lattice disturbance occurring due to vibration. Hence, for meeting phase noise requirements of PLL based high precision system (i.e. unmanned aerial vehicle (UAV), helicopter, missile, and other dynamic platforms) using reference source as clock requires development of improved design and compensation techniques to overcome such limitation. Fig. 1(a) shows the basic design of system using reference source [1], [2].