A mean square power detector system, comprising: a gain or attenuation circuit comprising a plurality of gain or attenuation elements (302, 602) arranged for generating a plurality of amplified or attenuated versions of a radio frequency input signal (RF in); a plurality of mean square detectors (102, 104) coupled to the gain or attenuation circuit, each of the mean square detectors receiving a different one of the plurality of amplified or attenuated versions of the RF input signal, each of said plurality of mean square detectors generating an output signal representative of the mean square power of the RF input signal for a different input signal level range; a summing element coupled to the plurality of mean square detectors for combining the output signals of the plurality of mean square detectors to generate a signal (MS out) representative of the mean square or root mean square of the RF input signal; and characterised by: a plurality of top limiting and bottom clipping elements, wherein each top limiting and bottom clipping element comprises an input coupled to an output of a different one of the plurality of mean square detectors and an output coupled to the input of the summing element; and wherein each top limiting and bottom clipping element is configured to top limit and bottom clip the output signal of the respective mean square detector to remove detected signal levels of the output signal outside an accurate squaring region of the respective mean square detector, wherein the top limiting and bottom clipping elements are configured to bottom clip the outputs of the mean square detectors to remove an inaccurate detection range resulting from noise or mismatch and to top limit the outputs of the mean square detectors to remove an inaccurate detection range resulting from shifting from squaring characteristics. a gain or attenuation circuit comprising a plurality of gain or attenuation elements (302, 602) arranged for generating a plurality of amplified or attenuated versions of a radio frequency input signal (RF in); a plurality of mean square detectors (102, 104) coupled to the gain or attenuation circuit, each of the mean square detectors receiving a different one of the plurality of amplified or attenuated versions of the RF input signal, each of said plurality of mean square detectors generating an output signal representative of the mean square power of the RF input signal for a different input signal level range; a summing element coupled to the plurality of mean square detectors for combining the output signals of the plurality of mean square detectors to generate a signal (MS out) representative of the mean square or root mean square of the RF input signal; and characterised by: a plurality of top limiting and bottom clipping elements, wherein each top limiting and bottom clipping element comprises an input coupled to an output of a different one of the plurality of mean square detectors and an output coupled to the input of the summing element; and wherein each top limiting and bottom clipping element is configured to top limit and bottom clip the output signal of the respective mean square detector to remove detected signal levels of the output signal outside an accurate squaring region of the respective mean square detector, wherein the top limiting and bottom clipping elements are configured to bottom clip the outputs of the mean square detectors to remove an inaccurate detection range resulting from noise or mismatch and to top limit the outputs of the mean square detectors to remove an inaccurate detection range resulting from shifting from squaring characteristics. a plurality of top limiting and bottom clipping elements, wherein each top limiting and bottom clipping element comprises an input coupled to an output of a different one of the plurality of mean square detectors and an output coupled to the input of the summing element; and wherein each top limiting and bottom clipping element is configured to top limit and bottom clip the output signal of the respective mean square detector to remove detected signal levels of the output signal outside an accurate squaring region of the respective mean square detector, wherein the top limiting and bottom clipping elements are configured to bottom clip the outputs of the mean square detectors to remove an inaccurate detection range resulting from noise or mismatch and to top limit the outputs of the mean square detectors to remove an inaccurate detection range resulting from shifting from squaring characteristics.