Multi-phase interleaved converters represent interesting solutions in terms of reduced current rating of each module, reduction of input and output current ripples, and possibility of redundancy. However, when attempt to interleave resonant converters operating at the same switching frequency, the resonant components' tolerance can cause severe current unbalance between them. In this paper, a two-phase interleaved LLC resonant converter is proposed that employs a current-controlled inductor to adjust the resonance frequency of one module, thus compensating for component mismatch. Experimental results of a prototype rated at 24V-12A output are presented, confirming the theoretical forecasts
In this paper, the susceptibility of a Kuijk bandgap voltage reference to electromagnetic interferences (EMIs) superimposed
to the power supply is investigated. A model of the bandgap circuit is derived from experimental tests consisting of scattering
parameters and susceptibility measurements on a test chip. The
model is able to correctly predict the susceptibility of the circuit by
means of SPICE transient simulations. The simulations identify the
fundamental stray components responsible for EMI coupling that
are usually not taken into account in postlayout analyses. From
the EMI point of view, the rectification phenomenon of bipolar
transistors, used in the bandgap cell, and the operational amplifier (op-amp) input distortion are shown to cause the voltage reference performance degradation. In particular, for the first time, the importance of the bandgap cell is pointed out, suggesting that the measures to reduce the susceptibility of the op-amp may not be sufficient to guarantee the bandgap immunity. Moreover, the analyses of main parasitic paths (from the power supply net to the more sensitive nodes) demonstrate the relevance of paths that are not commonly considered during the design phase and that may lead to an immunity degradation. Possible solutions to reduce the bandgap susceptibility are also explored, suggesting design criteria, filtering techniques, and layout variations. A second test chip is designed and manufactured to validate the suggested improvements and verify the critical role of the bandgap cell. Finally, a simplified theoretical analysis, which allows a fast bandgap susceptibility
evaluation, is presented. This tool is used to point out the importance of the rectification phenomenon compared to the
op-amp differential pair distortion
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