Enter your target Attenuation (dB) and Characteristic Impedance (Z₀) into the Bridged Tee Attenuator Calculator to find the exact resistor values you need — R1 and R2 — for a perfectly matched passive attenuation network.
Resistor R1
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Resistor R2
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A bridged-tee attenuator is an RF circuit topology that reduces signal power by a specific amount while maintaining impedance matching. It consists of two resistors arranged in a T-configuration with a bridging resistor across the input and output.
The bridged-tee attenuator uses resistive voltage division to reduce signal amplitude. The series resistor R1 drops voltage while the shunt resistor R2 provides the proper impedance match to maintain system characteristics.
Bridged-tee attenuators offer good input/output isolation, stable frequency response, and require only two resistor values. They are simpler than pi-pad attenuators and provide better isolation than simple L-pad configurations.
Use the formulas: R1 = Z₀ × (10^(A/20) - 1) and R2 = Z₀ / (10^(A/20) - 1), where A is attenuation in dB and Z₀ is the characteristic impedance in ohms.
Common RF system impedances are 50Ω (most RF systems), 75Ω (cable TV, video), and 100Ω (balanced systems). 50Ω is the most widely used standard in RF and microwave applications.
Bridged-tee attenuators work well for attenuation levels from 1dB to 40dB. Higher attenuation values may require impractically large or small resistor values and multiple stages may be preferred.
For precise attenuation, use 1% or better tolerance resistors. The actual attenuation will depend on resistor accuracy, so high-precision applications may require trimming or selection of exact values.