Impediments to impedance and coupled noise: characteristic impedance design and coupled noise control on flexible circuits

Signal integrity analysis is largely neglected in flexible circuit design. Referred to as "cables," ribbons or discrete connections, minimal, if any, analysis is typically performed. However, due to their ability to successfully address mechanical flexibility and cost constraints, flexible circuits have become increasingly appealing solutions for high-speed, controlled impedance interconnect. Design for signal integrity, characteristic impedance and attenuation control are critical to successfully placing flexible circuits in the highspeed market at GHz frequencies. This paper addresses the following: (1) mesh reference plane impedance prediction using solid plane techniques; (2) characteristic impedance variations caused by inconsistent orientation to reference planes; (3) uneven adhesive distribution in mesh reference constructs; (4) cross-talk resulting from signal-to-mesh orientation and dielectric separation; (5) material alternatives to lower dielectric loss in high-speed applications.