How much does a power supply filter in a data center switch improve CE (Conformance Efficiency)?

Data center switch power port filters significantly improve conducted emission (CE) performance. Actual test data shows: without filters, multiple frequency points in the 0.15MHz-30MHz band exceed the limit by 6-15dB; adding a single-stage filter (common-mode inductor CMZ7060A-701T 700Ω + X capacitor 0.22μF + Y capacitor 1000pF) results in an average reduction of 18dB, meeting Class A requirements with a 4dB margin; adding a two-stage filter (CMZ7060A-701T + CMZ3225A-501T 500Ω + X capacitor 0.47μF + Y capacitor 2200pF) results in an average reduction of 28dB, meeting Class B requirements with a 6dB margin. The common-mode inductor is the largest contributor to the reduction, accounting for approximately 65%, followed by the Y capacitor at 25%, and the X capacitor at 10%. The filter insertion loss and source impedance must be matched in the design.