A Technology Independent Synthesis Approach for Integrated mmWave Coupled Line Circuits

In this paper a technology independent approach for an efficient synthesis of coupled line circuits is presented. In contrast to conventional coupler design approaches, this synthesis method uses an additional process characterization step, which computes the electrical behaviour of these coupled lines in a given process layer stackup via even and odd mode simulations. Thus, the extracted behaviour information is used to determine the geometric values for a parametrized passive structure. Afterwards, a model and numerical based optimization is performed to improve the design with respect to a predefined specification target. To demonstrate this method, a Marchand balun was designed. The measured results of this balun show a maximum phase imbalance of 2° between 125 and 170 GHz and an insertion loss of maximum 2 dB for the entire D-Band.