expansion ratios provide mappings between nonlinear sensors and a more linear output domain the method includes a method of converting an input digital signal having a nonlinear dependency on a physical variable into an output digital signal that exhibits a substantially linear dependency with respect to the variable is disclosed the method includes multiplying the input digital signal by a variable multiplying factor to thereby generate a multiplied digital version of the input signal adding to the multiplied digital version of the input signal a predefined digital offset signal to thereby produce the output digital signal multiplying the output digital signal by a predefined feedback gain correction factor to thereby produce a digital feedback signal using the digital feedback signal to produce the variable multiplying factor application_number US 94809910 A description pad u00e9 approximants may be used to produce expandable approximations of desired mapping functions where the approximations may be expressed as a ratio of two power series where each power series includes a respective set of coefficients a given pad u00e9 approximant mapping function may be defined and or fined tuned by adjusting either or both of its numerator and denominator coefficients pad u00e9 approximation mapping functions are suitable for.