A stabilized, low-noise GaAs FET integrated oscillator with a dielectric resonator at C-band

TO USE G a h FET oscillators as power source in microwave communication systems, good temperature frequency-stability and low noise characteristic are essential’. A GaAs FET integrated oscillator stabilized with a high-Q dielectric resonator has been found to provide a highly-frequencystabilized, low-noise, compact RF power source. To realize optimal coupling between the oscillator and stabilizing resonant circuits, a large-signal design study was undertaken involving the measurement of the dynamic properties of the oscillator and resonant circuit. A stabilized oscillator output of 1OOmW with 17% efficiency and frequency temperature coefficient as low as 2.3 ppm/OC was obtained at 6-HGz. The FM noise characteristic has been improved more than 30dB by introducing the dielectric resonator. A common-source GaAs FET oscillator affords improved microwave performance through the optimization of the external feedback network. An unstabilized oscillator, with a series connection of microstrip lines and a dielectric capacitor as a feedback network2 generates 400-mW of microwave power with 38% efficiency at 6000MHq which is comparable to the maximum added power for an amplifier using an FET chip obtained from the same wafer.