Practical Consideration on Power Line Filter Design and Implementation

Electromagnetic interference filters have been studied extensively and proven to be a complex subject, with no single easy solution or rule of thumb. Typical filtering solutions for differential mode disturbances originating from a switched mode power supply are investigated in this paper. A simple T-shape filter model is used to derive an insertion loss equation that is dependent on source and load impedance, which allows to predict filter performance in more realistic settings compared to typical 50/50 Ω measurement setups. It concurs with observations made in a case study that changing filter orientation could increase filter performance.