Ka-band YIG-tuned GaAs oscillator

The design and preliminary test results of a new YIG-tuned GaAs oscillator covering the 26.5 to 40 GHz range are described. Diode evaluation, RF circuit, magnetic tuning circuit, RF performance, and magnetoresistance effects are considered. Refined circuit technology, minimizing the reactance of parasitic elements and proper impedance transformation, paid off in excellent tuning linearity. An efficient magnet structure with composite high-permeability magnetic alloys has shown negligible saturation effects. At high frequencies, it will be necessary to reorient the diode chip to prevent the magnetoresistance effect from occurring. The new device replaces the backward-oscillator tube as a local oscillator source in a tunable millimeter-wave receiver.