EMC analysis on field and circuit of PCB

In this paper, electromagnetic compatibility (EMC) of a four-layer printed circuit board (PCB) with the function of Digital-to-Analog conversion (DAC) is analyzed. The characteristic is explored by the method of combination of field and circuit. Resonance of power layer is simulated in SIwave and noise of critical signal lines are simulated in Designer. Based on the result of simulation, some improvement approaches are put forward and applied to the PCB design. Finally, the DAC of the board has accomplished and the frequency spectrum of analog waveform is measured by network analyzer. The result of measurement shows a pure sine spectrum with noise lower than - 45dBm.