The main functions of a PI-type attenuator are as follows:
- Precisely control signal amplitude to prevent circuit overload;
- Match the impedance of different modules to reduce signal reflection;
- Adjust the signal dynamic range to optimize system performance.
In a 50Ω system, the core formulas for calculating the resistor values of a PI-type attenuator (PI attenuator) are based on the characteristic impedance Z0=50Ω and the attenuation amount A (unit: dB). First, calculate the voltage attenuation coefficient k=10^(A/20) using the attenuation amount, then calculate the three resistors respectively:
- Series arm resistors:R1=R3=Z0*(k-1)/(K+1)
- Shunt arm resistor: R2=Z0*2k/(k^2+1)
(Note: Z0=50Ω，k=10^(A/20)，A is the required attenuation amount (in dB))