Synchronous rectified step-down converter susceptibility to conducted and radiated EMI

In this paper the susceptibility of synchronous rectified step-down converters to electromagnetic interference (100 kHz - 500 MHz) is examined and evaluated by experimental measurements. Performance degradation of linear low dropout regulators due to RF rectification and non-linear effects of RFI on error amplifiers is well documented. SR buck converters exhibit system stability and poor transient response behavior due to low-level RF injection and a complete circuit failure operation in presence of high-level RF injection. The use of L-C filter for RFI solution must be designed carefully as it can degrade the converterpsilas transient response.