Investigation on the limit quantization error for a general case of a three-voltage measurement method for ratiometric output sensors

A certain method for reducing quantization errors in output-supply voltage ratio measurement for a ratiometric sensor is discussed in the paper. This problem may occur when the ratio of two voltages is measured through individual measurement of each of them. The proposed method consists of measuring a third voltage being the difference between the two previously measured voltages. Expressing the result of the voltage ratio measurement as a certain function of the three voltage measurement results, a reduction of the voltage ratio limit error can be obtained. A general form of such a function is presented together with its parameters range for an error minimization criterion. The analysis made showed that the minimum of the limit error estimate is obtained when the two following voltages are measured: the third (differential) and the sensor output voltages which enables the limit error to be halved compared to the classic measurement where also two voltages are measured; this time the input and sensor supplying ones