Patent ID: 7391474

Claim:
A method of adjusting transfer functions of an error converter channel and a reference converter channel that can each amplify an analog input signal S with a fixed gain G and a programmed gain g and convert the amplified signal to a corresponding digital code, the method comprising the steps of: with a selected gain value of the programmed gain g, determining a first error parameter E rr1 as ΔC err /ΔC ref wherein ΔC err and ΔC ref are code differences of said error converter channel and said reference converter channel that correspond to an analog input signal difference ΔS; with a selected signal value of said analog input signal S, determining a second error parameter E rr2 as 2[(C err2 /C err1 )/(C ref1 /C ref2 )]−1 wherein C err1 and C err2 are codes from said error converter channel and C ref1 and C ref2 are codes from said reference converter channel that respectively correspond to first and second programmed gains g 1 and g 2 ; forming first and second correction parameters α and β to respectively be 1/E rr1 E rr2 and (1−E rr1 )/E rr1 E rr2 ; and modifying the programmed gain of said error converter channel to be αg+β.