I'm trying to design a Sallen-Key BPF within Matlab. With the documentation found on ti: http://www.ti.com/lit/ml/sloa088/sloa088.pdf, I studied and understood the basic.
As for the design: The center frequency of my BPF is 40kHz. Q-factor and gain at center frequency must be 1. So in matlab I've made:
Fm = 40000; R1 = 10000 R2 = 10000 C = 10*10^-9 R = 1/(2*pi*Fm*C); G = 1+(R2/R1); Q = 1/(3-G); Am = G/(3-G); w = 2*pi*Fm; B=[G*R*C*w 0 ] A=[(R^2)*(C^2)*(w^2) R*C*w*(3-G) 1] sys=tf(B,A) bode(sys,opts);
The issue is that my resulting bodeplot is indeed showing a BPF behaviour, but not at the desired frequency. Furthermore.
Can someone explain this to me? Thanks in advance