A Ka-Band Monolithic Doubly Balanced Up- and Down-Conversion Mixer

This paper presents a Ka-band doubly balanced ring mixer implemented by 0.13-μm GaAs mHEMT MMIC process. In this design, modified Marchand baluns are employed to improve balun's balance performance, achieve good port matching and simplify intermediate frequency (IF) extraction. Measured results show good agreement with the simulations for both upand down-converter applications. The mixer exhibits 6.3-10 dB conversion loss with greatly improved return loss of the LO/RF/IF port. The LO-to-RF, LO-to-IF and RF-to-IF isolations are better than 40 dB, 28 dB and 15 dB, respectively.