Constant edge rate output driver
AssigneeNational Semiconductor Corporation
InventorsRichard W. Cook, Steven M. Macaluso
Life of this patent
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Abstract
In a circuit and method for adjusting rise-and-fall-time changes in an output driver signal due to changes in temperature, process or voltage, the driver output voltage is monitored and current flow through a constant load resistor adjusted as the voltage changes. The current may be adjusted by controlling the gate-source voltage on a transistor. The gate voltage on the transistor may also be used to adjust the power supply to pre-drivers of the output driver.
Claims12
A method of compensating for rise/fall time variations in the signal from an output driver due to process, voltage or temperature variations, comprising
- monitoring changes in output voltage from the output driver due to process, voltage or temperature variations, and
- providing a compensation circuit that supplies a feedback voltage that changes in sympathy with the output voltage change due to rise/fall time variations, wherein the compensation circuit includes a pseudo-rail circuit for generating power supply voltages that change in sympathy with the output voltage change due to rise/fall time variations.
Dependencies are inferred from the claim text.