A Circuit Model for Electromagnetic Suppressing Spurious Noise of Synchronous DC-DC Buck Convertor

This paper presents the analysis of electromagnetic noise for a synchronous DC-DC buck convertor. The ripple noise is the fluctuation of output voltage caused by the incessant charging and discharging of the energy storage inductor and capacitor during the MOSFET on and off, and the ripple noise voltage up to 11 mV superimposed the parasitic parameters of the inductor and capacitor effect on the output voltage. The oscillation noise is caused by the resonance of the parasitic inductor and capacitor of the MOSFETs and the output LC filter. In addition, this paper constructs RFPA circuit using a synchronous DC-DC buck convertor, and presents a circuit model which can suppress the electromagnetic noise of buck convertor.