Method and device for measuring resistances using a direct interface circuit

The number of digital systems that use sensors is growing day by day. These systems require analog-to-digital signals conversion methods. The most popular way to do is by using a direct interface circuit. Due to its intermediate results in measuring time and accuracy, the most frequently used method is the two-point calibration method. However, new ways to reduce the measuring time of the direct circuit interface are needed. In this way, researchers from a Electronics department in a Southern Spanish University have developed two new methods that reduce the measuring time up to 55% without any additional hardware costs. These methods have been compared against the traditional two-point calibration method without showing a lack of accuracy. Two fast calibration methods, Fast Calibration Method I (FCM I) and Fast Calibration Method II (FCM II) have been tested and compared against the two-point calibration method using known values of the resistance and a field-programmable gate array operating with different voltages. All methods have very similar curves, but FMC II shows a lower accuracy for higher resistances. Instead, the two-point method and the FMC I method show the same behavior in all the ranges. Regarding the time reduction for estimating the resistance value, the values of TRmax (condenser discharge time) and Tmax (total time to measure resistance) for the values of the constant Tx used for comparisons. TRmax has the same value, no matter the method. However, Tmax is always smaller when using FCM II. Reduction in TRmax against TPCM (Two-Point Calibration Method) oscillates between 17% and 62% while reduction in Tmax oscillates between 9.5% and 55%. Companies in the electronics sector who wish to implement and commercialize the technology via license agreement are sought.