Abstract

A M.M.I.C. realization of voltage controlled oscillator (V.C.O.) for X-BAND application and frequency stabilization is presented Fig.l. Conventional V.C.O. is based on the association of a Ga As MESFET and a varactor diode followed by a buffer amplifier.Among them ,an original one is proposed here:it is mainly based on the suppression of the varactor diode.Instead , the variations of a HEMT gate-to-source capacitance allow to realize frequency variation on the oscillator.This approach offers good frequency stability,low tuning sensitivity to temperature,low phase noise and obviously simpler design. On the other hand,the .present configuration of the microwave oscillator can be used to realize an injection-locked oscillator.For this purpose, we suggest an alternative approach for the design of stabilized microwave source without cavity-stabilization , such as dielectric resonator (DRSO) , or phase locked loop (PLL) system in order to obtain both simpler design and good performance such : high temperature stability and linear amplitude modulation with low cost and small size.