Enter your Characteristic Impedance (Z₀) and desired Attenuation (dB) to calculate the resistor values for your Pi Attenuator network — the calculator returns R1, R2, and the Attenuation Ratio (K) so you can size your shunt and series resistors without the manual math.
R1 Resistance
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R2 Resistance
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Attenuation Ratio (K)
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Enter the characteristic impedance (typically 50Ω or 75Ω) and desired attenuation in dB. The calculator will compute the required R1 and R2 resistor values for your pi attenuator circuit.
A pi attenuator is a resistive network shaped like the Greek letter π, consisting of two series resistors (R1) and one shunt resistor (R2). It reduces signal amplitude while maintaining impedance matching.
Common values are 50Ω for RF systems and test equipment, and 75Ω for video and cable TV applications. Some specialized systems use other values like 25Ω or 100Ω.
The attenuation ratio K is calculated as 10^(dB/20), where dB is the desired attenuation. For example, 20 dB attenuation gives K = 10.
R1 = Z₀ × (K+1)/(K-1) and R2 = Z₀ × (K²-1)/(2K), where Z₀ is characteristic impedance and K is the attenuation ratio.
Yes, you should select the closest standard resistor values to the calculated results. Small deviations typically have minimal impact on performance.
Pi attenuators are used in RF circuits for signal level adjustment, impedance matching, isolation between circuit stages, and reducing reflections in transmission lines.