Monolithically integrated push-pull driver

摘要

Push-pull driver with reduced noise generation resulting from driver switching. A further transistor is arranged between the driver output transistor (which becomes conductive at the low output level) and the chip ground line. Its base is connected to a reference voltage source the other pole of which is connected to the ground plane of the circuit card to which the corresponding semiconductor chip is attached. If a noise voltage is generated on the chip ground line, the emitter potential of the further transistor is pulled up. As its base potential is maintained at a fixed value by the applied reference potential, this transistor becomes less conductive. As a result, the rate of current change in the output stage is reduced. The slowed down current rise, leads to a reduced noise voltage developing on the common chip ground line. According to another embodiment of the invention the output transistor and said further transistor are combined to form one transistor whose base is maintained at a fixed voltage by means of two series-connected Schottky diodes.