<P>PROBLEM TO BE SOLVED: To provide a multimode VCO which includes a function to absorb phase hits over a tuning range of operation and operates reliably at a low cost. <P>SOLUTION: A tunable oscillator includes a first transistor, a second transistor connected in parallel with the first transistor, a noise feedback and bias network coupled to the first and the second transistors, a planar coupled resonator network coupled to the first and the second transistors, and a means for dynamically tuning the resonant frequency of the planar coupled resonator network and the junction capacitance of the first and the second transistors. The dynamic tuning means has a plurality of capacitive elements coupled so as to lie astride each junction of the first and the second transistors. The capacitive element has a varactor diode coupled in series to a first capacitor and a second capacitor coupled in series to the varactor diode. <P>COPYRIGHT: (C)2007,JPO&INPIT 
USER-DEFINABLE, LOW COST, LOW PHASE HIT AND SPECTRALLY PURE TUNABLE OSCILLATOR