Compatible EMI filters

A vexing problem in electromagnetic compatibility is the effective filtering of conducted interference from power-supply lines. Because of unavoidable and severe mismatch, conventional suppression filters operate only conditionally; such filters are often so large they are omitted from the system. Three new classes of power-line filters without these limitations are described. They are active, truly lossy, and ruggedized ceramic filters, covering the frequency range from direct current to microwaves. Present filter test methods are shown to be misleading and are replaced by a rather simple, realistic test.