Patent ID: 6057891
Filing Date: 2000-05-02
Classification: H03M

Abstract:
Process for correcting the value of an input quantity X of an analog/digital converter delivering a digital output quantity Y dependent on the value of the quantity X, the output value Y exhibiting n values Y.sub.0, . . . , Y.sub.n-1 regularly spaced by a spacing .DELTA.Y when X varies from a value X.sup.0 to a value X.sub.n-1, Y exhibiting the value Y.sub.0 when X has, to within a spacing, the value X.sub.0, the value Y.sub.n-1 when X has, to within a spacing, the value X.sub.n-1 and n-2 intermediate values Y.sub.1, Y.sub.2, . . . , Y.sub.n-2 resulting from the quantity X, on the one hand through a linear transformation of the form Y=a.sub.0 X+b.sub.0, and on the other hand, through a quantization Y, Y retaining the same output value Y.sub.p when X varies from a value X.sub.p-1 to a value X.sub.p, the value Y.sub.p being one of the values obtained from the linear transformation when X varies between X.sub.p-1 and X.sub.p, in which process corrections are performed during conversion suspension periods interposed between periods of conversion, so as to inject known values of the input quantity X into the converter and calculate therefrom correction values to be applied, the process being characterized in that during one or more conversion suspension periods and in a continual iterative manner throughout conversion,a) measuring output values Y.sub.m1, . . . Y.sub.mn for an integer number m of input values X.sub.m1, . . . , X.sub.mm ;b) calculating the actual conversion line from the resulting m measurements using the equation Y=a.sub.1 X+b.sub.1, this line being the nearest to the m points with co-ordinates X.sub.m1, Y.sub.m1 ; X.sub.m2, Y.sub.m2 ; . . . ; X.sub.mm, Y.sub.mm,c) correcting the offset error by adding the algebraic value of the difference b between b.sub.1 and b.sub.0 to the analog input quantity,d) correcting the gain of conversion by multiplying the input quantity X by the latest calculated ratio a.sub.1 /a.sub.0.