(2st order, 12 dB/octave, Highpass)
C=4.7n-10nF
<math>Ra=\frac {0.7071}{2\pi \times Fc \times C}</math>
<math>Rb=\frac {1.414}{2\pi \times Fc \times C}</math>
Units: Rx [Ω], C [F], Fc [Hz]
