This paper investigates several factors affecting EMI-performance of digital controllers targeted at conducted-noise reduction in dc-dc converters. Four factors have been studied: frequency modulation profile, randomization ratio percentage, clock frequency, and spread-spectrum scheme. The field-programmable gate arrays (FPGAs) have made substantial improvements in price and performance throughout the past few years. All investigations have been accomplished by using FPGA-based implementations. A breadboard circuit has been built-up for the experimental investigations. Furthermore, a comparative study has been carried-out to comprehensively understand the effect of such factors on conducted noise mitigation. A substantial part of the manufacturing cost of power converters involves designing filters to comply with the EMI limits. Considering these investigations when designing the dc-dc power converters significantly reduces the filter size.