No abstract

To meet antenna design specifications under realistic conditions, electromagnetic coupling effects between the antenna and its environment must be considered. In this work, an efficient antenna design optimization methodology that considers the influence of the human head and main mobile handset components on the antenna performance is presented. The computational optimization time is dramatically reduced by exploiting a Broyden-based input space mapping (SM) algorithm. Both coarse and fine models required for the SM algorithm are based on the finite-element method and are implemented in the same simulator; simplifying the modeling process. However, our coarse model does not consider any object of the actual operational environment. In spite of that and other simplifications applied to the coarse model, the proposed optimization scheme is able to find a solution that meets the specifications in a realistic environment by performing an extremely small number of expensive fine model simulations. Our practical illustration opens up the feasibility of using this CAD methodology to optimize other RF devices that operate in close proximity to objects that affect its desired response, as it is the case for many wearable devices.

Highly efficient CAD methodologies based on full wave EM analysis, for the design of package interconnects are necessary due to the increased frequencies of operation and a desire of faster time-to-market. In this work, we exploit a Broyden-based input space mapping (SM) algorithm with both fine and coarse models implemented with the finite-element method (FEM), to efficiently optimize design parameters of a modern package interconnect. This optimization algorithm has been applied to a single-ended package line resulting in a significant decrease of the return loss in the 5-10 GHz range, requiring just a few fine model evaluations.Index Terms -space mapping, package interconnects, EM based design optimization, high-speed, return-loss, FEM.

We demonstrate Ge-on-Si metal-semiconductor-metal (MSM) photodetectors monolithically integrated with silicon oxynitride (SiOxNy) waveguides. The waveguide is placed on top of the photodetector and between the metal electrodes, evading the shading effect by metal electrodes, which is typical in surface-illuminated MSM photodetectors. The devices showed responsivity of about 0.45 A/W for 80 μm long devices at 1550 nm. The photodetector with 1.5 μm electrode spacing showed 3 dB bandwidth of 2.0 GHz at −2 V and 2 μA dark current. Further studies suggest that with a modified design the structure is capable of achieving 1 A/W responsivity and greater bandwidth.

No abstract