Diagnosis of EMI to laptop WWAN device from TFT-LCD driver using non-contact measurement-based transfer function technique

This paper presents a novel non-contact measurement technique for electromagnetic interference (EMI) diagnosis. The proposed technique uses vector network analyzer with antenna and near-field probes to measure the transfer function for an EMI path without interrupting the operation of device under test. As an example, with the help of the measured transfer function and equivalent source in the proposed technique, the EMI to laptop wireless wide area network (WWAN) device caused by a thin film transistor-liquid crystal display (TFT-LCD) driver is accurately diagnosed and appropriately treated. In addition, an easy-to-follow procedure is given for applying the presented non-contact measurement technique to the demonstrated example.