This paper aimed at modeling EMI noise source of the continuous current mode (CCM) DC-DC converter. To this end, this paper focuses on the reverse recovery phenomenon of Si and SiC diodes which is induced in its turn-off operation. This paper also studies the effect of the input voltage level on the recovery current and on the conducted EMI noise in CCM DC-DC boost converter under periodic steady-state operation. The result shows that the terminal capacitance of diodes determines the noise spectrum distribution especially for higher than 30 MHz.