Broadband Planar Ring Mixers with DGS-Marchand Baluns in the Millimeter Wave Frequency Range

Planar hybrid ring mixers in the millimeter wave range for frequencies up to 80 GHz are presented. They exhibit conversion losses lower than 15 dB up to frequencies higher than 70 GHz, with a very wide IF-bandwidth range from DC up to 22 GHz. The balancing of the input signals is realized by using broadband DGS-Marchand baluns, thus enabling an operation bandwidth of the mixers of more than 80%. The very high couplings at the baluns are realized by applying defected ground structures to the backside metallization of the circuits. The mixer circuits can be easily integrated into larger circuits. The design and the measurement results for three different mixer realizations are presented and compared.