Two transistor flyback converter design for EMI control

A two transistor flyback converter using current mode, pulse width modulation (PWM) control for the control of radiated emissions is studied. The design and layout of an existing power supply using this type of converter were analyzed and high radiation sources were located. Changes were implemented and evaluated in an anechoic chamber. The radiation was reduced by a new layout of the critical signal paths that are incorporated in the design. This improvement was made without changing the power supply performance as there were no added components in the high-voltage switching circuitry. Guidelines for the layout implementing the changes are derived for this type of converter or other converters with similar architecture