How to avoid resonance in multi-stage filtering of power line carrier PLC?

To avoid resonance in multi-stage filters of a power line carrier PLC, it is necessary to rationally design the parameters of each filter stage and the damping network. First, the frequency response of each filter stage is analyzed through circuit simulation to avoid overlapping resonance peaks. In LC filters, series damping resistors are used, such as parallel resistors (10-100Ω) across the inductor or series resistors (1-10Ω) across the capacitor, to reduce the Q value and broaden the resonance peak. Multi-stage filters with different resonant frequencies are used; for example, the first stage cutoff frequency is set to 1MHz, the second stage to 500kHz, and the third stage to 200kHz, forming a stepped filter. A PBZ1608A-102Z0T ferrite bead is used as a high-frequency damping element, whose resistive characteristics effectively suppress resonance. In actual testing, a spectrum analyzer is used to scan the system frequency response to ensure there are no resonance spikes in the carrier frequency band. Through optimization, the system gain fluctuation is made less than 3dB in the 10kHz-30MHz range, avoiding signal amplification or attenuation caused by resonance.