A passive circuit for addition and subtraction of transducer signals with independent scaling

A simple passive circuit for addition and subtraction of transducer signals is described. Output signals of the circuit are the independently scaled sum and difference of the input signals. The circuit is an entirely passive special resistor bridge that makes high accuracy and long-term stability feasible. By selection of proper technology the circuit can be miniaturized and fabricated for operation over a very broad temperature range. The influence of internal admittances of real transducers on the circuit performance is also analyzed. Conditions for cancelling unwanted influence are determined. The circuit has been verified experimentally and some practical applications are demonstrated