An 8-18-GHz YIG-Tuned FET Oscillator

We report here on the design and construction of a YIG- tuned FET oscillator tunable over the entire 8-18-GHz frequency range. The minimum output power from this device operating into a 50-omega load is about +6 dBm. The addition of a balanced buffer amplifier increases the power to about + 12-dBm minimum. When optimized for the 12-18-GHz band, the oscillator alone generates a minimum of + 10 dBm. The oscillator/ amplifier combination produces at least +15 dBm. We discuss a number of difficulties inherent in the design of broad-band oscillators, especially fixed frequency resonances, linearity, and power drop outs at the low end of the frequency range.