High pass filter Using Inductor or a capacitor


So I was thinking about making a basic Highpass filter. I was wondering if there was any reason to use an RL configuration as opposed to a CR configuration.

Best Answer

Your question touches another question: "What is the advantage of active RC filters if compared with passive RLC topologies?".

Answer: One of the advantages is the avoidance of inductors because inductors (if compared with capacitors) have larger dimensions and more weight and tuning is problematic. More than that, they are more expansive and have very bad EMC capabilities (they are "good" antennas) and their IC-capabilities are limited.

For these reasons methods have been developped to realize active inductances (opamp-based RC circuits) or to replace inductances in passive RLC circuits with resistors applying the so-called "Bruton transformation".

However, for high frequencies inductances are still be used due to the limited frequency capabilities of opamps.