The filter shown in the figure, using only an operational amplifier, is characterized by allowing 1 kHz signals to pass freely, which are amplified 200 times, with signals from other frequencies being rejected. The quality factor of this circuit (factor Q) is 50 and the central operating frequency, as we said, is 1 kHz, but with the change in the values of the twin T, other operating frequencies can be achieved. The components that determine the frequency are R2, R3 (which are the same); R4 which must be half of R2 and R3, C2 C3 which are equal and finally C4 which must be twice as much as C2 and C3.
| Clique na imagem para ampliar |
