A 10–110GHz fundamental/harmonic rat-race mixer

This paper describes a broadband 10-110 GHz mm-wave rat-race ring diode mixer. The mixer can be used as a fundamental mixer as well as a harmonic mixer. The finite- ground-width CPW on a 15 mil alumina substrate is used to implement the circuit. The mixer is designed to allow DC bias that a local power as low as 0 dBm could properly pump the mixer. Two commercial available M/A-Com MA4E2037 GaAs beam-leaded Schottky diodes are used. The measured conversion loss is typically 9 dB from 10 to 100 GHz in the fundamental mixing mode and 15 dB from 20 to 110 GHz in the harmonic mixing mode.