Patent ID: 7714694

Claim:
A method for providing a trimmable resistive component having a predetermined behavior of temperature coefficient of resistance (TCR) as a function of trimming, the method comprising: selecting materials to form a compound resistor having at least a first portion and a second portion, at least said first portion including a first resistor R 1 , that is thermally trimmable and has a first resistivity, a first temperature coefficient of resistance value α 0 , and a trimming-induced shift of temperature coefficient γ 1 , which defines a change in said α 0 per fraction of trimming x of said first resistivity, said second portion including at least a second resistor, R 2 , having a second resistivity value, and a second temperature coefficient of resistance value β 0 ; determining how said TCR value of said resistive component changes as at least said first portion is trimmed, by generating a function of said TCR versus trim-fraction x, with R 1 and R 2 as variable parameters and α 0 , β 0 , and γ 1 as fixed parameters; and selecting specific values for R 1 and R 2 or R 1 /R 2 to provide said resistive component with said predetermined behavior of said TCR, thereby incorporating an effect of said γ 1 in said resistive component, with γ 1 being (a) a constant or (b) a function, γ 1 (x), representing fixed behavior of γ 1 as a function of trim-fraction x.