PCB access impedances extraction method of in-situ integrated circuit

Abstract

This article describes an extraction technique of input and output impedances of integrated circuits (ICs) implemented onto the printed circuit boards (PCBs). The feasibility of the technique is illustrated with a proof-of-concept (POC) constituted by two ICs operating in a typically transmitter-receiver (Tx-Rx) circuit. The POC system is assumed composed of three different blocks of emitter signal source, load and interconnect passive network. This latter one is assumed defined by its chain matrix known from its electrical and physical characteristics. The proposed impedance extraction method is elaborated from the given signals at the transmitter output and receiver input. The terminal access impedances are formulated in function of the parameters of the interconnect system chain matrix. The feasibility of the method is checked with a passive circuit constituted by transmission lines driven by voltage source with RL-series network internal impedance and loaded at the output by the RC-parallel network. Good correlation between the access impedance reference and calculated is found.