I have opened a question yesterday regarding a mistake I am not finding in my Deliyannis and Friend design algorithm: Deliyannis-Friend design: where is my mistake?
Although I am still trying to find the problem it is starting to become clear for me that \$ \beta \$, the ratio of resistors might not actually be a degree of freedom. Or rather, if we take it as a degree of freedom that will change \$ Q \$ and \$ K_p \$ both alone or simultaneously. What I am starting to think is that perhaps \$ Q \$ will be fixed, \$ K_p \$ inevitably changes and then another resistor might need to be added for gain correction... But that seems to turn it to a very complex problem. Does anyone know any step by step design method for the Deliyannis Friend biquadratic section, knowing the three parameters of the transfer function? There seems to be a lack of bibliography regarding this important filter and I am having a lot of trouble solving this problem. Thank you.
