PROCESS FOR COMPENSATING COMPONENT TOLERANCES IN ANALOG-DIGITAL CONVERTERS

摘要

The proposal is for a process for compensating component tolerances of a series of similar components, especially capacitors (C1a to C8) in analog-digital converters which are connected to a shared line and the electrical value of which is halved from one component to another, in which the lowest-value component (C1a, C1b) is doubled. In this process, a first potential (Vdd) is first applied to at least one of the components (C8) and a second potential (Vss) is applied to the other lower-value components (C1a to C7). A comparator (12) then checks whether the median potential (Vm) between the two potentials (Vdd, Vss) is present on the shared line (16). To a correcting component (Ck) also connected to the shared line (16) is then applied a variable correcting voltage (Vk) which is tuned until the comparator (12) finds the median potential (Vm) on the shared line (16). Finally, the correcting voltage (Vm) so found is stored as a correcting value. It is thus possible to tune each of these components individually and compensate tolerance errors so that individual subsequent calibrations can be made which only very briefly interrupt the conversion operation of the analog-digital converter. The precision and linearity of an analog-digital converter fitted with such a tuned capacitor array are very great.