Representation of the algebraic sum of two voltages - their sum is represented as voltage based on reference potential

摘要

The two voltages are not connected with the reference voltage, but are connected in series as in a Thomson bridge consisting of four resistors, but not directly connected in series with each other; junction points in each resistor pair are connected to the inputs of a differential amplifier; its noninverting input is connected to the reference potential through a fifth resistor; or the star circuit consisting of the above four resistors and two resistors in series with the amplifier inputs are replaced by a triangular circuit of four resistors derived in pairs from the resistor in series with the amplifier inputs, omitting the original four resistors; the fifth resistor and an amplifier feed-back resistor have the same value.