Importance

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Abstract

A push-pull output driver includes a pair of auxiliary, low current capacity output circuits connected in parallel with a pair of high current capacity, series connected devices. In response to a pulse transition at the input of the driver circuit, one of the high current capacity devices is turned on to provide the current necessary for a change in state of the output signal. After the output signal has reached a steady state level, the associated auxiliary low current capacity device is turned on and the high current capacity device is turned off. For the remainder of the duration of the pulse, the relatively low current required to maintain the output signal is provided by the auxiliary gate. At the next pulse transition, the other of the high current capacity gates is turned on. Since the first high current capacity gate was turned off prior to the pulse transition, only one of the high current capacity devices is drawing current from the supply and the need for a large current supply is eliminated. The circuit of the invention allows for the design of very high speed drivers and the totem pole currents which are the source of Delta-I noise do not occur. The driver includes a pulse circuit responsive to voltage levels of the driver output terminals to selectively turn off the primary, high current carrying capacity gates and to selectively turn on and off the auxiliary gates.

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First Claim