Buffered RC band-pass calculator

Calculate a buffered RC high-pass and low-pass cascade without interstage loading.

Schematic

Try in CircuitSim

Loading CircuitSim schematic…

Results

Center frequency503.29 Hz

Frequency response

Gain

Frequency: 500 Hz

Gain at selected frequency	0.91 V/V
Gain	-0.83 dB
Phase	0.22 °

Advanced results

Peak gain	0.91 V/V
Lower −3 dB frequency	134.37 Hz
Upper −3 dB frequency	1.89 kHz
−3 dB bandwidth	1.75 kHz

How buffered rc band-pass works

C1/R1 form the high-pass stage, a unity-gain op amp isolates it, and R2/C2 form the low-pass stage. The buffer removes interstage loading. Each RC corner is a stage corner; the combined −3 dB band is measured relative to the combined peak.

H(s)=\frac{sR_1C_1}{(1+sR_1C_1)(1+sR_2C_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
C1	100 nF
R2	10 kΩ
C2	10 nF
V1	500 Hz

First RC corner: $f_1=1/(2\pi R_1C_1)$
$\frac{1}{2\pi\times1\,\mathrm{ms}}$
≈ 159.15 Hz
Second RC corner: $f_2=1/(2\pi R_2C_2)$
$\frac{1}{2\pi\times100\,\mathrm{\mu s}}$
≈ 1.59 kHz
Center frequency: $f_0=\sqrt{f_1f_2}$
$\sqrt{159.15\,\mathrm{Hz}\times1.59\,\mathrm{kHz}}$
≈ 503.29 Hz
Peak gain magnitude: $|H(f_0)|=|b_1|/a_1$
$\frac{1\,\mathrm{ms}}{1.1\,\mathrm{ms}}$
≈ 0.91 V/V
Gain at selected frequency: $|H(j2\pi f)|$
$f=500\,\mathrm{Hz}$
≈ 0.91 V/V

Buffered RC band-pass calculator

Configure

Schematic

Results

How buffered rc band-pass works

Explore more calculators

RC low-pass filter

RC band-pass filter

Inductive reactance

Learn more