Controllable di/dt push/pull driver
AssigneeInternational Business Machines Corporation
InventorGene J. Gaudenzi
Life of this patent
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Abstract
A driver circuit to limit the di/dt downgoing transition to a desired value employs an active feedback path. The driver circuit utilizes a Schottky Barrier Diode as a current bleed to limit the base current of the drive circuit transistor. The active feedback path includes a normally conductive transistor which turns off when the output falls to a predetermined level. Elimination of the active feedback path in this condition insures maximum DC drive.
Claims6
A circuit for limiting the time-rate of change of down-going transitions of a signal present at the output terminal of an active collector driver, comprising a first transistor having a base coupled to a signal input terminal and a collector coupled to a means for providing a supply voltage and an emitter coupled to ground, a second transistor having a collector coupled to said output terminal and an emitter coupled to ground for pulling-down said signal present at said output terminal to a low state, impedance means coupled to said first transistor and the base of said second transistor for limiting the base current of said second transistor, pull-up means coupled to said output terminal for pulling-up said signal present at said output terminal to a high state, a feedback path coupled to said output terminal and said impedance means for limiting said time-rate of change of said downgoing transition of said output signal, and switch means for clamping said feedback path to ground.
Dependencies are inferred from the claim text.