Abstract
To predict electromagnetic (EM) noise emission from a signal line on a digital printed circuit board (PCB), we propose an equivalent circuit model of CMOS logic IC which requires less calculation time and simple procedures in modeling. In this paper, we described characteristics of the model and the procedure to determine parameters. Calculated voltage waveform of IC output was first compared with measured one. Calculated result of the fall time as a function of load capacitance was very similar to the measured one. Spectra of output voltage are also close to each other between them. Spectral profile is -20dB/dec in the low frequencies, which becomes to be -40dB/dec in the higher frequency region. EM spectra were then calculated, resulting in the peak height 6dB larger than the measured one when the load capacitance was large. Calculated spectral profiles, however, agree approximately with measured ones.
