Hi,
I'll check that out. In the mean time ignore that equation and you can use the first equation or check this next one out which is much simpler.
But take another look at your plot. Remember you have to look at the straight line segment to see the -40dB/decade. It actually is -40dB/decade.
Also, in view of the fact that you dont mind using the second resistor being equal to 10 times the first and the second capacitor 10 times less than the first cap, we can get to an estimate this way which is much faster...
R1C1=sqrt(sqrt(18081*A^2+4000000*Vin^2)-241*A)/sqrt(200*A*w^2)
where
A is the peak to peak voltage,
So once we calculate R1C1 we divide that by C1 and we get the value of the first resistor:
R1C1/C1=R1
and since R2=10*R1 and C2=C1/10 we have all four components. The only value we have to choose is C1.