In multilayer printed circuit boards, the noise on the power bus is influenced by the impedance between the power and ground planes. Power-bus noise estimates require an accurate estimate of the power-bus input impedance. This paper develops a closed-form estimate of the input impedance for circular power-return plane structures. When the structure is lossy (e.g., boards employing embedded capacitance or densely populated boards), the energy reflected from the board edge does not significantly affect the input impedance. In general, the expressions developed here for circular structures can be used to estimate the impedance of lossy power-return plane structures of any shape.


Electrical and Computer Engineering

Keywords and Phrases

EMC; Capacitance; Circular Power-Return Plane Structures; Closed-Form Expression; Conductive Loss; Densely Populated Boards; Dielectric Loss; Electric Impedance; Embedded Capacitance; Input Impedance; Lossy Structure; Multichip Modules; Multilayer PCB; Multilayer Printed Circuit Boards; Noise; Noise Suppression; Power-Bus Input Impedance; Power-Bus Noise Estimates; Printed Circuits; Reflected Energy

International Standard Serial Number (ISSN)


Document Type

Article - Journal

Document Version

Final Version

File Type





© 2003 Institute of Electrical and Electronics Engineers (IEEE), All rights reserved.

Publication Date

01 Jan 2003