A constant voltage constant current wheatstone bridge configuration

For many measurement applications a Wheatstone bridge configuration can be used to measure physical quantities, such as pressure, force or velocity. Offset behaviour plays a vital role in the overall accuracy. Often, ambient temperature changes cause undesired changes in parameters that are supposed to be constant.In this paper, an integrated silicon double bridge configuration is presented using a sophisticated sensor biasing principle in one bridge, whilst simultaneously maintaining the supply current and the supply voltage constant.Sensor biasing is achieved by using thermal feedback between the two bridges. Applying this principle will reduce drift to a large extent and may even make laser or any other trimming procedure obsolete. Moreover, full integration of the sensor and the signal processing parts, consisting of complicated highly accurate analogue circuits, is possible due to the constant parameters provided. To demonstrate the utility of this concept, an integrated silicon anemometer is described.