public override void Update()
{
double x = this.parameters[P_VOL];
double C1 = 200e-9f;
double C2 = 0.0002e-6f;
double R2 = 100e3f*(1-x);
double R1 = 100e3f*x;
//double R3 = 140e3f;
double[] b = {0, C1*R1, C1*C2*R1*R2};
double[] a = {1, (C1*R1+C1*R2+C2*R2), C1*C2*R1*R2 };
double[] zb, za;
Bilinear.Transform(b, a, out zb, out za, this.fs);
this.B = zb;
this.A = za;
}