Artificial neural network modeling for computer-aided design of microwave and millimeter-wave circuits

A novel approach for accurate and efficient modeling of passive microwave/mm-wave components by using electromagnetically-trained artificial neural network (EM-ANN) software modules is presented. Artificial neural networks are employed to model complex relationships between physical parameters of a component and the corresponding electrical response. Full-wave EM analysis is employed to characterize passive components. Structures for simulation are chosen using design of experiments (DOE) methodology. Analysis EM-ANN models are then trained using physical parameters as inputs and component response (i.e. S-parameters) as outputs. In addition, synthesis models can be developed by interchanging the inputs and outputs used for component characterization. Methods for incorporation of prior knowledge (existing models) for model development have been explored. It has been demonstrated that use of prior knowledge (when it exists) reduces the number of EM simulations that are needed to characterize the component to be modeled. Once trained, the EM-ANN models can be inserted into a commercial microwave circuit simulator where they provide results approaching the accuracy of the EM simulation tool used for characterization of the microwave/mm-wave components without increasing the analysis time significantly. The proposed technique is capable of providing models for simulation and optimization of microwave/mm-wave components where models do not exist or are not accurate over the desired region of operation.; EM-ANN modeling of microstrip vias and multilayer interconnects is demonstrated. An example of using EM-ANN models to optimize component geometry is included for a stripline-to-stripline multilayer interconnect. A methodology for the synthesis (leading to physical dimensions) of multilayer asymmetric coupled microstrip lines using ANN models is presented. Both synthesis and analysis models have been developed. Models are appropriate for synthesis of multilayer structures like filters, baluns, and directional couplers. EM-ANN modeling has also been used for generating a library of component models for CPW circuit design. Design and optimization of a CPW folded double stub filter and a 50 {dollar}Omega,{dollar} 3 dB power divider circuit, using the developed CPW EM-ANN models, has been demonstrated. Research has also been conducted on novel CPW patch antennas. Using EM-ANN modeling techniques, a wide bandwidth CPW patch antenna has been designed and validated by both EM simulation and measurements. A discussion of these results and ideas for future research are presented.