A sigma-delta modulator (300) comprising a first filter stage (304); a second filter stage (306) in series with the first filter stage (304); a first feedback path (311) between the output of the second filter stage (306) and the input to the second filter stage (306), the first feedback (311) comprising a first gain stage (308, 308′) such that the first feedback path (311) is configured to provide a first gain value; and a second feedback path (313) between the output of the second filter stage (306) and the input to the first filter stage (304), the second feedback path (313) comprising a second gain stage (309; 310′) such that the second feedback path (313) is configured to provide a second gain value. The first gain value is different to the second gain value.