Shown here are two block diagrams contrasting the single-ended and differential approaches. The first diagram represents the single-ended block diagram with a small, one-sided input signal. The blue signal illustrates any sort of common mode interference coming into the system. Note that this blue interference signal is also amplified at the output – it is amplified just as much as the desired signal. It is difficult to separate the desired signal from the interference signal. The differential block diagram shows the desired signal made up of two signals of opposite polarity, one is positive and the other is negative. Any interference introduced at the inputs would ride the same on both reference levels, as illustrated in blue. Although the interference signals are amplified at each output, when looking at the composite signal, the difference between the two differential signals, the desired signal is doubled, and the interference has been removed. While the single-ended approach is susceptible to common mode noise, power supply noise, or EMI, the differential block has an immunity to those interferences by the virtue of cancellation.