A broadband, planar, doubly balanced monolithic Ka-band diode mixer

A planar monolithic diode mixer that achieves 5-10-dB conversion loss and very low distortion and spurious responses over a 26-40-GHz RF and local oscillator (LO) bandwidth and DC-12-GHz IF is described. Two types of diodes have been used: the first used the gate-to-channel junctions of 0.2- mu m*80- mu m InGaAs HEMTs; and the second used Schottky diodes realized in HBT technology. The baluns are Marchand-like coplanar structures. >