This article proposes a comprehensive analysis and prediction method for wafer-level radiated electromagnetic interference (EMI) based on integrated circuit (IC) source modeling. An IC and a simplified wafer-level package (WLP) with a redistribution layer (RDL) were designed and fabricated for the research. The IC that draws currents through the RDL is efficiently modeled as a Thevenin equivalent circuit in the frequency domain. The equivalent EMI source model can simply replace complex time-domain operations of the IC that cannot be easily implemented in a full-wave field solver. To simulate the radiated EMI from the wafer-level RDL, the EMI source model is incorporated into the full-wave solver. The proposed approach is validated by comparing the simulated fields using the EMI source model and the measured fields on the WLP. The tendency of the radiated fields shows a high correlation with the common-mode current flowing through the RDL. The IC source modeling approach enables the decomposition of EMI factors into an IC operation and WLP structure.

Electronic devices usually operate in a variable loading condition and the power transfer efficiency of the accompanying wireless power transfer (WPT) method should be optimizable to a variable load. In this paper, a reconfigurable WPT technique is introduced to maximize power transfer efficiency in a weakly coupled, variable load wireless power transfer application. A series-series two-coil wireless power network with resonators at a frequency of 150 kHz is presented and, under a variable loading condition, a shunt capacitor element is added to compensate for a maximum efficiency state. The series capacitance element of the secondary resonator is tuned to form a resonance at 150 kHz for maximum power transfer. All the capacitive elements for the secondary resonators are equipped with reconfigurability. Regardless of the load resistance, this proposed approach is able to achieve maximum efficiency with constant power delivery and the power present at the load is only dependent on the input voltage at a fixed operating frequency. A comprehensive circuit model, calculation and experiment is presented to show that optimized power transfer efficiency can be met. A 50 W WPT demonstration is established to verify the effectiveness of this proposed approach.