The differential-to-common-mode conversion is specified to control the injection of commonmode noise from the cable assembly into the host or device. Figure 3-43 illustrates thedifferential-to-common mode conversion (SCD12/SCD21) requirement . A mated cableassembly passes if its SCD12/SCD21 is less than or equal to −20 dB from 100 MHz to 10 GHz.