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US 4,883,979 AGranted
Darlington BiCMOS driver circuit
AssigneeTexas Instruments Incorporated
InventorHiep V. Tran
Life of this patent
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Abstract
A driver circuit is provided which offers decreased input loading, increased output loading, and a high voltage output level corresponding to a logic-1. These results are achieved through the use of pull-up transistors and capacitive and resitive circuitry which allow bootstrapped voltages.
Claims8
A BiCMOS driver circuit comprising:
- a first CMOS inverter;
- a first bipolar transistor connected to the output of said first CMOS inverter;
- a second bipolar transistor connected to the base of said first bipolar transistor;
- a second MOS inverter connected to the base of said second bipolar transistor;
- voltage pull-down circuitry connected to the output of said first bipolar transistor.
2 more elements
An improved driver circuit of the type including a first inverter connected to a first bipolar pull-up transistor including a parasitic capacitance between the base and emitter of the latter, wherein the improvement comprises:
- connecting a second bipolar pull-up transistor to said first bipolar transistor;
- and
- providing a resistance path within said first inverter capable of permitting said parasistic capacitor to boot said base of said first bipolar pull-up transistor above the driver circuit supply voltage so as to raise the emitter voltage of said first bipolar pull-up transistor to substantially the level of the supply voltage.
Dependencies are inferred from the claim text.