Design precise Pi attenuator circuits with our free online calculator. Quickly determine the series and shunt resistor values (R1, R2, R3) for RF and audio applications. Ideal for impedance matching and signal level reduction, simply input your desired attenuation in dB and characteristic impedance (Zo) for instant results. Optimize your electronic designs efficiently and accurately for passive attenuation.
Formula:
Pi Attenuator Resistor Formulas
To calculate the resistor values for a symmetrical Pi attenuator, we first determine the attenuation factor 'N' and then apply the following formulas:
- N (Attenuation Factor): N = 10(dB / 20)
- R1 (Shunt Input Resistor): R1 = Zo × ((N + 1) / (N - 1))
- R2 (Series Resistor): R2 = Zo × ((N2 - 1) / (2N))
- R3 (Shunt Output Resistor): R3 = R1
Where:
- Zo = Characteristic Impedance (Ohms)
- dB = Desired Attenuation (Decibels)
- N = Attenuation Factor (unitless, ratio of input voltage to output voltage)
Note: For 0 dB attenuation, R1 and R3 will be infinite (open circuit), and R2 will be 0 (short circuit).