Contactless measurement of in-circuit reflection coefficients

Abstract

This paper presents a new method for the contactless measurement of in-circuit reflection-coefficients (Γinsitu). The proposed method relies on an electromagnetic (EM) model of a known passive structure (e.g. a bondwire array) that can be embedded in any unknown circuitry. By operating the circuit to be investigated normally and probing locally the EM field induced by the known structure inside this circuit, the in-circuit reflection coefficients at boundaries of this structure under the actual operating conditions can be directly obtained. The proposed method is demonstrated on a single bondwire and verified by a set of independent measurements. The high potential of the proposed method for future applications is demonstrated by applying it to a bondwire array that mimics the output connections of a large-periphery high-power device.