A bipolar transistor circuit is disclosed, which receives input voltage signals (125,126) and outputs a current I₀ of a polarity in accordance with the input signals and of a predetermined amplitude. This circuit includes a first current source (Q₄, Q₅) producing a first reference current, an output terminal, bipolar switching transistors (Q₉-Q₁₂) coupled between the first current source and the output terminal (124) and controlled by the input voltage signals to supply to the output terminal an output current of a first polarity which has an amplitude of the first reference current minus a base current of the switching transistor or integer times of that amplitude, a current producing circuit (Q₁₃, Q₁₄) producing a current that is substantially equal to the base current of the switching transistor, and a second current source (Q₈) connected to the output terminal and producing a second reference current of a second polarity which has an amplitude of the first reference current minus the amplitude of the current produced by the current producing circuit. The present invention thus provides a well-balanced output current which is suitable to charge and discharge a load capacitor with the same amount of charges.
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