A Second-Order Low-Pass Filter is a dynamic electrical circuit, classified as a second-order linear time-invariant system, that selectively attenuates high-frequency components of an input signal while permitting low-frequency components to pass with a roll-off rate of -40 dB/decade above the cutoff frequency, distinguished from first-order low-pass filters by its use of two energy-storing elements (typically inductors and capacitors or operational amplifier-based equivalents) that introduce a second-order differential equation governing its input-output relationship.