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].