High-performance GaAs beam-lead mixer diodes for millimetre and submillimetre applications

A novel GaAs beam-lead Mott Schottky-barrier mixer device having a zero-bias junction capacitance near 10 fF, very low parasitic capacitance, ideality factor near or below 1.07, and a zero-bias cutoff frequency as high as 5000 GHz has been developed. The diode configuration makes use of a unique design in which the current distribution in the N+ layer at d.c. and at r.f. are equivalent, and thus, for the first time, it is possible to fully characterise mixer devices at d.c. Samples of these devices have been tested at 94 GHz in a broadband fin-line mixer structure, and realised a mixer conversion loss below 6.0 dB. This performance is representative of the best results achieved to date in a printed-circuit mount.