Signal integrity constrained optimization of flexible printed interconnects for mobile devices

This paper presents a systematic procedure for optimizing the geometry of high-speed data links based on Signal Integrity constraints. The structures under consideration are flexible printed circuits typically found in mobile devices having moving parts. Since the geometry of such interconnects is approximately translation-invariant, we adopt multiconductor transmission line models, characterized by broadband frequency- dependent per-unit-length parameters that implicitly account for losses and dispersion. Each interconnect is characterized by several geometrical and material parameters, which con- stitute the free variables for optimization of the link. Signal integrity constraints such as return loss, impedance, attenuation, or ultimately eye diagram opening are used as goals in a closed-loop optimization process. We employ an efficient model parameterization scheme based on the Generalized Method of Characteristics to reduce the number of RLGC computations and to convert the parameterized model into a SPICE-ready deck for transient simulation and eye diagram generation under realistic loading conditions. Several numerical results illustrate the feasibility of the approach. I. INTRODUCTION