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This paper presents a novel fully integrated step-up dc/dc converter containing circuits to improve electromagnetic emissions. This design utilizes current sources to limit the impulsive current flow into the integrated flying capacitors. This reduces the discontinuous pulse currents normally associated with capacitive converters causing electromagnetic interference (EMI). A variable reference current enables the converter to operate with the lowest possible emissions through the entire operating range and is used to regulate the output voltage. The inclusion of low EMI techniques enables fully integrated power converters to be implemented in systems where noise produced by converters currently restricts or prohibits their use. The proposed 3.2 mW voltage doubler was fabricated in a 0.18 $\mu$m CMOS process. With an input voltage range of 1–1.8 V, the converter produces a 1.6–3.3 V output. Experimental results verify the reduction of emissions to meet IEC 61967-4 Class L using current control with a reduction of noise voltage when compared with the circuit without the proposed techniques. [ABSTRACT FROM AUTHOR]

The objective of this paper is to present a methodology for identifying the current flow in the capacitors of a multiphase buck converter by synchronously measuring the capacitor currents. A multiphase buck converter uses multiple parallel buck converters with different switching times to source a large amount of current. Currents in the primary capacitors of a multiphase buck converter are drawn by all phases of the converter; however, the phases switch asynchronously. Synchronizing to the switching of a specific phase reveals how the current from that phase is distributed among the capacitors throughout a circuit board. The proposed measurement method is illustrated by comparing an initial printed circuit board design to a new design to show the effect of better capacitor placement and the addition of a ground plane. The new design confines the phase currents to the capacitors close to the field effect transistors of the specific phase. [ABSTRACT FROM AUTHOR]

Ringing in the switching waveform of the switching power supply (e.g., synchronous buck converter) is known to cause broadband electromagnetic interference problems in the 30–300 MHz range. The measured switching waveform shows overshoot and, then, exponential decay of the ringing. It has been observed that this exponential decay rate varies significantly between using different low-side FETs; thus, the low-side FET dominates the attenuation of the ringing. This paper provides a novel method for quantifying the losses by using the measureable quantity “ Ross,” which is equivalent to the loss of the output capacitance C oss of the FET. This paper describes the method of measuring Ross and explains its relevance to the self-damping of the switch ringing. The method permits selection of a low-side FET to optimize the electromagnetic compatibility performances of the supply. [ABSTRACT FROM AUTHOR]