Biased K-band LTCC star mixer with substrate-embedded dielectrics

A biased star mixer at K-band is presented. The design is realized in low temperature co-fired ceramics, benefiting from the possibility of including printed dielectrics with a high relative permittivity between layers. With this feature, small scale DC-blocks are introduced to the Marchand balun in order to allow for the application of an external bias voltage. Simulation shows that the wide bandwidth characteristic is not reduced by the additional feature. Also an acceptable port isolation is obtain. Instead, the LO drive level can be significantly reduced. Measurements prove the proper functionality of the mixer.