Components R12, R17, and C16, C18, C21 provide the ability to apply common-mode and differential-mode filtering to the inputs. The cutoff frequencies for the filters are shown in Equation 1 and Equation 2. Make C18 approximately ten times larger than C16 and C21. These calculations presume R12 = R17 and C16 = C21. The correlating resistors and capacitors provide input filtering for channel B.

Common-mode cutoff frequency:

Equation 1.

Differential-mode cutoff frequency:

Equation 2.