1. An apparatus including a sigma-delta difference-of-squares RMS-to-DC converter, comprising: analog signal multiplication and combining circuitry responsive to an analog input signal and at least first and second analog feedback signals by providing a resultant analog signal that includes at least one signal component corresponding to a difference between a square of said analog input signal, a square of said first analog feedback signal and said second analog feedback signal; analog signal filter circuitry coupled to said analog signal multiplication and combining circuitry, and responsive to said resultant analog signal by providing a filtered analog signal; analog-to-digital conversion (ADC) circuitry coupled to said analog signal filter circuitry and responsive to said filtered analog signal by providing a related digital output signal; digital-to-analog conversion (DAC) circuitry coupled to said ADC circuitry and responsive to said digital output signal by providing an analog signal; first feedback circuitry coupled between said DAC circuitry and said analog signal multiplication and combining circuitry, and responsive to said analog signal by providing said first analog feedback signal; and second feedback circuitry coupled between said DAC circuitry and said analog signal multiplication and combining circuitry, and responsive to said analog signal by providing said second analog feedback signal.