Design and evaluation of controlled impedance PCBs for high frequency applications

Operating speeds of data handling systems for onboard spacecraft applications are ever increasing so as to meet the performance requirements like high resolution, stereoscopic imaging etc., of complex remote sensing payloads. In such applications, the Printed Circuit Boards (PCBs) used for realization of hardware are not simple interconnection platforms only, but are required to provide matched impedance interconnections between devices. They are required to include physical circuit configurations that have characteristic impedance with close tolerances as per the required design. This paper discusses the involved process in design, analysis and evaluation of such printed circuit boards. It uses the model suggested in the IPC 2141 document for conducting a sensitivity analysis of characteristic impedance as a function of process parameters. It discusses the production flow in a practical situation for a design up to 350 Mbps LVDS signals. Practically realized parameters have shown an excellent match with the design requirements and the system performance has met all the functional requirements.