Multiple-feedback band-pass calculator

Calculate center frequency, bandwidth and peak gain of an inverting MFB band-pass filter.

Schematic

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Results

Center frequency1.67 kHz

Frequency response

Gain

Frequency: 1.67 kHz

Gain at selected frequency	5 V/V
Gain	13.98 dB
Phase	179.72 °

Advanced results

Peak gain	5 V/V
Lower −3 dB frequency	1.52 kHz
Upper −3 dB frequency	1.84 kHz
−3 dB bandwidth	318.31 Hz

How multiple-feedback band-pass works

The input reaches a shared node through R1, with R2 to ground. C1 connects that node to the summing input, C2 connects it to the output, and R3 closes the resistive feedback path. Both feedback paths shape the pass band.

f_0=\frac{1}{2\pi}\sqrt{\frac{1/R_1+1/R_2}{R_3C_1C_2}}

Ideal op-amp equations with ±15 V supplies. The simulated generic op amp has finite bandwidth and output limits. Keep signal levels within its linear range.

Change the form inputs or click a component value on the schematic. Choose Try in CircuitSim to simulate the configured circuit.

Do the math

Selected input values
R1	10 kΩ
R2	1 kΩ
R3	100 kΩ
C1	10 nF
C2	10 nF
V1	1.67 kHz

Center frequency: $f_0=\frac{1}{2\pi}\sqrt{\frac{1/R_1+1/R_2}{R_3C_1C_2}}$
$\frac{1}{2\pi\times95.35\,\mathrm{\mu s}}$
≈ 1.67 kHz
Peak gain magnitude: $|H(f_0)|=\frac{R_3C_1}{R_1(C_1+C_2)}$
$\frac{10\times10\,\mathrm{nF}}{20\,\mathrm{nF}}$
≈ 5 V/V
Bandwidth: $BW=\frac{C_1+C_2}{2\pi R_3C_1C_2}$
$\frac{1}{2\pi\times500\,\mathrm{\mu s}}$
≈ 318.31 Hz
Gain at selected frequency: $|H(j2\pi f)|$
$f=1.67\,\mathrm{kHz}$
≈ 5 V/V

Multiple-feedback band-pass calculator

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Schematic

Results

How multiple-feedback band-pass works

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