A new doubly balanced sub-harmonically miniature mixer using dual Marchand balun in CMOS 0.18-µm technology

In this paper, a new doubly balanced sub-harmonically resistive mixer topology is presented. In this new topology, 2LO-to-RF isolation can be improved compared with singly balanced resistive mixer. The twice of LO frequency signals are cancelled due to differential property. Moreover, in order to generate two the differential signal sets, miniature transformer based Marchand dual baluns are implemented in the mixer design. This circuit has a measured conversion loss of 7 dB of RF frequency from 25 to 40 GHz, and 2LO-to-RF isolation better than 35 dB, with a chip size 450 × 450 µm². To the author´s knowledge, this mixer occupies the smallest size (λ/13)² with good performance for MMW application.