Design of miniaturized common-mode filter by multi-layer low temperature co-fired ceramic

A miniaturized common-mode filter composed of multiple substrates is proposed in this paper. The pattern of each positive coil is interlaced with that of each negative coil, whereby when the positive and negative coils are alternately stacked, the positive coils do not overlap negative coils. With such offset configuration of the coils, the parasitic capacitance introduced between overlapped traces is reduced. So, the thickness of each substrate can be decreased and the size of the entire filter is effectively reduced. Good agreements between simulated and measured results are demonstrated. Further, the effectiveness of this filter is revealed by radiation spectrum measurements.