A simple accurate bridge-transducer interface with continuous autocalibration

This paper presents a one-chip simple and accurate transducer interface for resistive bridges. A key part of this interface is formed by a novel dynamic voltage divider, In this divider the bridge supply voltage is measured for reference purposes in small parts (piece-wise measurement) which are within the range of the bridge output voltage. The use of an autocalibration technique, the three-signal method, eliminates influence of linear parameters and errors. Moreover, the effects of the nonidealities of the applied switches are also eliminated. The circuit has been realized in a 3 mu m BiCMOS process and shows an uncertainty of only 10 mu V for a bridge supply voltage of 5 V.