A novel current-based approach for very low variation detection of resistive sensors in wheatstone bridge configuration

Here we present a new approach, based on current signals, suitable for the detection of very low variations of resistive sensors in a Wheatstone bridge configuration. It has been implemented in Current-Mode (CM) approach by employing the positive Second Generation Current Conveyor (CCII+) as basic active block. This solution shows high common mode cancellation, high sensitivity, high accuracy, linear response and easiness of offset compensation of the bridge unbalancing, without any changing of its elements, so optimizing also gain and resolution. Its main performances have been preliminary evaluated through PSpice simulations employing the AD844 by Analog Devices. The achieved results show a good agreement with theoretical calculations and demonstrate the validity of the new idea. It results to be suitable for resistive full-bridge configurations showing a capability to detect theoretically relative variations of resistors lower than 0.0001% with a bridge output voltage sensitivity up to 10V/%.