Noncontact Time-domain EMI Measurement of Two Adjacent Traces on a PCB

Nonintrusive electromagnetic interference (EMI) detection is a powerful method for EMI diagnosis in high-speed links and multiple signal PCB designs. However, due to the dispersive nature of signal delivery passages and interferences from neighborhood signals, it is very difficult to locate exactly the EMI source of two adjacent traces without contact. In this paper, a noncontact time-domain voltage measurement method is proposed to detect the EMI signals of two adjacent traces on a PCB. A near-field electric probe is employed and a reconstruction algorithm is developed to recover the voltage signals without contact. Through experimental benchmarks, it is demonstrated that the proposed method can successfully recover the common signals, differential signals, and non-correlated signals from the adjacent dual traces. It provides a convenient EMI source measurement method for high-speed and multiple signals PCB diagnosis and optimizations.