Output buffer with slew rate control utilizing an inverse process dependent current reference
AssigneeAdvanced Micro Devices, Inc.
InventorsRandall Biesterfeldt, Bryan Heenan
Life of this patent
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Abstract
An output driver circuit that provides more constant slew rates in the presence of process, voltage, or temperature variations that affect performance. An open ended (no feedback) solution is utilized that provides more constant slew rates in spite of PVT variations. A first performance dependent current and a reference current are generated and a third current is generated that is inversely related to performance utilizing the reference current and the performance dependent current. The third current is supplied to a gate of a first transistor circuit forming a portion of the output driver to thereby control the slew rate.
Claims23
A method comprising reducing slew rate variations of an output of an output driver circuit of an integrated circuit by generating and supplying a first input current to a gate of a first transistor of the output driver circuit having a magnitude that is inversely related to integrated circuit performance.
A method of reducing variation in slew rate of an output driver of an integrated circuit comprising:
- generating a first performance dependent current;
- generating a reference current;
- generating a third current inversely related to performance utilizing the reference current and the performance dependent current;
- and
- supplying the third current to a gate of a first transistor circuit forming a portion of the output driver to thereby control the slew rate.
An integrated circuit comprising:
- an output circuit including a first transistor coupling an output terminal of the integrated circuit to a first power supply node when data to be output by the output circuit is at a first value, the first transistor being coupled to receive a first gate current inversely related to performance of the output circuit.
An apparatus comprising:
- a transistor of an output buffer circuit coupling an output of the output buffer circuit to a first power supply node when data to be output by the output buffer is at a first value;
- and
- means for supplying a gate current to a gate of the transistor that is inversely proportional to an increase in performance of the integrated circuit due to at least one of process variation, voltage, and temperature variation.
Dependencies are inferred from the claim text.