Monolithic voltage controlled oscillator for X- and Ku-bands

The implementation of two varactors on monolithic GaAs circuits to achieve tuning bandwidths of 11.15-14.39 GHz and 16-18.74 GHz, thus covering the X- and Ku-bands, is reported. The 1.1 x 1.2 mm chip was a voltage-controlled oscillator circuit which included a 300-micron FET, bypass capacitors, tuning inductors, and isolation resistors. One of the varactors was placed at the source and the other in the gate circuits. Details of the design process are reviewed, with emphasis on techniques that allow prediction of the oscillator bandwidth. Techniques are defined for making correct choices of circuit configurations and the varactor ratio.