Jadax
Newbie level 4
Hi guys, I'm going through some preparatory work for my classes in Fall and in the main question I need to use ISIS to implement a third order low pass Bessel filter, described by the following normalised transfer funtion:
H(s) = 15/(s3 + 6s2 + 15s + 15)
And with a cutoff frequency of 10kHz.
I've used the following website (**broken link removed**) to model my sallen-key circuit on and have the following values of R/C to to achieve my 10kHz cutoff frequency:
R1=9.0269k R2=14.399k R3=7.2144k C1=1.5n C2=2.2n C3=470p (this is theoretical work as of now, which is why the values are ofc not of real components)
1. The thing is, the transfer function listed on that website for the above values of R/C is not the required transfer function I noted above. I don't understand why? could someone please explain to me what I am doing wrong.
2. I need to find the differential equation relating the output voltage (Vout) and the input voltage (Vin). How would I go about doing that?
H(s) = 15/(s3 + 6s2 + 15s + 15)
And with a cutoff frequency of 10kHz.
I've used the following website (**broken link removed**) to model my sallen-key circuit on and have the following values of R/C to to achieve my 10kHz cutoff frequency:
R1=9.0269k R2=14.399k R3=7.2144k C1=1.5n C2=2.2n C3=470p (this is theoretical work as of now, which is why the values are ofc not of real components)
1. The thing is, the transfer function listed on that website for the above values of R/C is not the required transfer function I noted above. I don't understand why? could someone please explain to me what I am doing wrong.
2. I need to find the differential equation relating the output voltage (Vout) and the input voltage (Vin). How would I go about doing that?