Hi guys :) I'm going through some prep. work for my modules in Fall and I've come across a question I'm having some difficulty with. 1. The problem statement, all variables and given/known data The question has a transfer function for which I need to find the differential equation relating the output voltage and the input voltage. 2. Relevant equations Transfer function: H(s) = 15/(s3 + 6s2 + 15s + 15) 3. The attempt at a solution I created the above circuit using a 3rd order sallen-key lowpass filter as in this website:http://sim.okawa-denshi.jp/en/Sallenkey3Lowkeisan.htm. I then split the circuit into 3 parts - A,B,C. I then deduced 3 voltage equations for the 3 nodes using kirchoffs circuit laws as follows; Va = (Va-Vin)/Z1 + (Va-Vb)/R2 + (Va-Vout)/Z2 = 0 Vb = (Vb-Va)/R2 + (Vb-Vout)/Z2 + (Vb-Vc)/R3 = 0 Vc = (Vc-Vb)/R3 + (Vc-0)/Z3 = 0 where Vc = Vout. Are the above equations correct? I'm not very comfortable with 3rd order circuits as of yet, and am not sure if I got the equations right. I've gotten to this point, but after this I'm not sure what I need to do. If I simply the above equations I will get the transfer function, but that's not what I want to find, how do I proceed from here?