Bandpass filter circuit composed of single power supply op amp 8FC7

The figure shows a single-supply low-voltage band-pass filter circuit. This circuit uses a single power supply operational amplifier 8FC7 to form a second-order band-pass filter , and the power supply voltage range can be from 3V to 30V. When determining the values ​​of each component, first determine the center frequency f0 of the bandpass filter , and then select the appropriate capacitor C (C=C1=C2) according to the table below. Then select the Q value. The Q value is a parameter that represents frequency selection characteristics. The higher the Q value, the narrower the passband. When Q=10, a frequency response characteristic of -40dB per octave can be obtained. But the Q value is too large and the circuit stability is poor. Generally, the Q value is chosen to be less than 10. The closed-loop gain K should ensure that the output amplitude is as large as possible without distortion. Generally KF is less than l. Finally, R1, R2, and R3 are calculated from the following three formulas.