PCB power/ground plane edge radiation excited by high-frequency clock

This paper describes the PCB power/ground plane edge radiation excited by a high-frequency clock, when it passes through power/ground plane pair by a through-hole signal via. For the analysis, the clock excitation mechanism was invested by TDR-TDT measurement and simulation with balanced TLM and via coupling model. Also, the power/ground plane edge radiation excited by sweeping from 100 MHz clock to 2900 MHz clock were measured. The power/ground plane edge radiation comes from voltage noise in the power/ground plane. From TDR-TDT investigations, we knew that a transition part in time domain makes the voltage noise, which has a strong relation with power/ground plane impedance depending on plane resonances and return current discontinuity of through-hole signal via. Therefore, the consecutive transitions of the clock make larger noise voltage and edge radiation. The PCB power/ground plane edge radiations of a clock depend on the power/ground plane impedance where the clock spectrum is varied. The higher power/ground plane impedance makes the larger power/ground plane edge radiation, when the clock frequency is fixed. In other words, the clock frequency and its harmonics go into the higher power/ground plane impedance range, the power/ground plane edge radiations are increased by maximum 35 dBm in near field measurement.