EMS Analysis on Digital Pulse Width Modulators

Conference: CIPS 2008 - 5th International Conference on Integrated Power Electronics Systems
03/11/2008 - 03/13/2008 at Nuremberg, Germany

Proceedings: CIPS 2008

Pages: 6Language: englishTyp: PDF

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Orietti, Enrico; Spiazzi, Giorgio (Department of Information Engineering (DEI), University of Padova, Padova, Italy)
Saggini, Stefano (Department of Electrical, Management and Mechanical Eng. (DIEGM), University of Udine, Udine, Italy)
Mattavelli, Paolo (Department of Technologies and Management of Industrial Systems (DTG), University of Padova, Vicenza, Italy)

In this paper, a digital pulse width modulator (DPWM) is analysed from the point of view of the susceptibility to radio frequency interferences (RFI). The chosen DPWM architecture is based on the hybrid delay-line/counter scheme commonly used in the digital control of switched mode power supplies, since it increases the DPWM performance in terms of maximum switching frequency, duty-cycle precision and area consumption. This paper focuses on the DPWM performance degradation in presence of electromagnetic interferences (EMI) and, for this purpose, a hybrid PWM with time resolution down to 350 ps has been designed and manufactured in a standard 0.35 µm CMOS technology. Measurements and analytical analyses are presented for both EMI effects on the internal generated clock signal and on the PWM duty-cycle precision. The immunity degradation mechanisms are investigated, in particular by means of the proposed mathematical approach, demonstrating that the PWM susceptibility is strictly related to its functional design.