NOVELTY - The circuit has a current mirror (100) including an input branch (101) series-connected with a resistive element (104) between two nodes (IN1, IN2) of application of a circuit voltage (Ve). A mirror output branch (103) provides a current (Is) representative of the voltage, and is located between one of the nodes and a third node (GND) of application of a reference voltage. A converting element (105) converts the current into an output voltage (Vs). The mirror includes bipolar transistors series-connected with a resistor, and a compensating circuit compensates transistor base current.    USE - Differential voltage measurement circuit for controlling differential voltage of series connected elementary or voltage generation cells of an electric battery (all claimed). Can also be used for a photovoltaic generator type application, and a fuel cell type application.    ADVANTAGE - The circuit controls differential voltage of the series connected elementary or voltage generation cells of the electric battery in an inexpensive, accurate, simple, and more secure manner with lower power consumption by using the current mirror without a need of a power supply, so that risks of circuit degradation and electrocution are decreased as circuit input terminals directly receive the voltage of the battery cells during handling operations of the circuit, thus efficiently protecting the circuit referenced to a same ground potential, and decreasing a number of digital-to-analog converters necessary to sample output voltage of the converting element of the circuit.    DETAILED DESCRIPTION - The transistors are MOS transistors, FETs, JFET transistors, PNP bipolar transistors and NPN bipolar transistors.    DESCRIPTION OF DRAWING(S) - The drawing shows a circuit diagram of a differential voltage measurement circuit.    Nodes of application of circuit voltage (IN1, IN2, GND)    Current (Is)    Circuit voltage (Ve)    Output voltage (Vs)    Current mirror (100)    Input branch (101)    Mirror output branch (103)    Resistive element (104)    Converting element (105)