Patent ID: 7545302

Claim:
An apparatus including a sigma-delta difference-of-squares RMS-to-DC converter, comprising: analog input signal router circuitry responsive to an analog input signal by providing first and second routed analog input signals related to said analog input signal; first analog signal combining circuitry coupled to said analog input signal router circuitry and responsive to said first and second routed analog input signals and first and second routed analog feedback signals by providing first and second combined analog signals related to respective combinations of said first routed analog input and feedback signals and said second routed analog input and feedback signals, respectively; analog signal multiplication circuitry coupled to said first analog signal combining circuitry and responsive to said first and second combined analog signals by providing an analog product signal including at least one signal component corresponding to a difference between a product of said first and second routed analog input signals and a product of said first and second routed analog feedback signals; analog signal filter circuitry coupled to said analog signal multiplication circuitry and responsive to said analog product 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; and signal conversion circuitry coupled between said ADC circuitry and said first analog signal combining circuitry, and responsive to said digital output signal by providing said first and second routed analog feedback signals.