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Abstract-Switched circuits are widely used, particularly for power electronic applications in which efficiency is important. Of these applications, the class-E amplifier has been given particular attention, since it is theoretically a 100% efficient switched circuit that has been successfully demonstrated in applications such as ballasts, converters, frequency multipliers and communication amplifiers at frequencies as high as 10GHz. However, with increasing power or frequency, nonlinearities become extremely important, for instance, in order to achieve actual class E operation and even to avoid destruction of the switching device.In this paper, a new method for determining the steady-state response of nonlinear circuits containing ideal switches is proposed. While the method is more general, the description is based on the Class E amplifier because of its inherent interest. The method is based on a time-domain Gear discretization of the circuit equations. A technique for determining the initial samples of the discretized equation of each topology is developed, based on the fact that state variables are constant during switching. Finally, assuming a periodic steady-state, a single algebraic system of nonlinear equations is obtained in which the unknowns are the samples of the control variable of the nonlinearity in the whole signal period. To validate the method described, a comparison with PSpice simulations is provided.

Developing new power converters often requires the measurement of current transients in transistors once they are positioned on its definitive location at the final PCB layout. Noninvasive conventional measuring methods such as active current probes or current transformers require a minimum space around the path of the current under measurement, but that space is not always available on definitive PCBs. The Rogowski current transducer is built by a flexible and thin coil, offers low insertion losses and a high bandwidth, so it is commonly used when space restrictions are important. New semiconductors such as SiC mosfets allow faster switching transients and therefore higher dv/dt occurs, leading to important perturbations on the Rogowski coil. This letter presents a two-step measurement procedure that allows the rejection of this perturbation. After a first conventional measurement, a second measurement, not encircling the current under study, is performed. During the second measurement the Rogowski coil is located close to the initial position, thus the second measurement records only the dv/dt perturbation. This perturbation can be easily subtracted to the first measurement, and therefore a perturbation-free current evolution is obtained.Index Terms-Rogowski current transducer, dv/dt immunity, switched current measurement, SiC mosfet

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