Planar Schottky barrier microwave mixers and varactors in gallium arsenide

The use of thin epitaxial layers in conjunction with planar Schottky barrier junctions on GaAs has produced very high "Q" microwave devices. With the barrier metal extended over a SiO2layer this "expanded" contact is wire-bonded to eliminate the metal springs that are found in the very small mesa structures or point contact diodes of conventional construction. Fabricated as a microwave mixer diode, typical noise figures of 5.0 to 5.5 db overall are measured at room temperature for X-band, including 1.5 db for the 30 Mc. IF amplifier. The best downconverter operation is obtained at 0.5 to 0.6 volts forward bias with the local oscillator injection power reduced to less than 200 microwatts. The mixer diode has also been fabricated in a small symmetrical package to permit application at various frequencies. State-of-the-art measurements will be given for frequencies into Ku band.