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RC Filter Calculator

RC Low-Pass Filter

Fill in any two fields and hit Calculate to solve for the third.

fc = 1 / (2π · R · C)

RC High-Pass Filter

Fill in any two fields and hit Calculate to solve for the third.

fc = 1 / (2π · R · C)

2nd-Order Sallen-Key High-Pass Filter

Fill in any four fields and hit Calculate to solve for the fifth.

Vin C1 C2 + − Vout R1 R2
fc = 1 / (2π · √(R1 · R2 · C1 · C2))

2nd-Order Sallen-Key Low-Pass Filter

Fill in any four fields and hit Calculate to solve for the fifth.

Vin R1 R2 + − Vout C2 C1
fc = 1 / (2π · √(R1 · R2 · C1 · C2))

2nd-Order Multiple Feedback (MFB) Low-Pass Filter

Fill in any four fields and hit Calculate to solve for the fifth. This is an inverting topology.

Vin R1 R2 C1 − + Vout C2
fc = 1 / (2π · √(R1 · R2 · C1 · C2))

2nd-Order Multiple Feedback (MFB) High-Pass Filter

Fill in any four fields and hit Calculate to solve for the fifth. This is an inverting topology.

Vin C1 C2 R1 − + Vout R2
fc = 1 / (2π · √(R1 · R2 · C1 · C2))