Processing circuitry may process a physiological signal such as a light signal attenuated by a subject. The physiological signal may include a desired component and an undesired component. A first filtering operation may be performed to remove at least a portion of the undesired component and a second filtering operation may be performed to reduce an undesired distortion introduced by the first filter. The transfer function of the second filter may be substantially the inverse of the transfer function of the first filter. One or more physiological parameters may be determined based on the filtered physiological signal.
