Simple output buffer drive strength calibration
AssigneeMicron Technology, Inc.
InventorTerry R. Lee
Life of this patent
Estimating the term…
Abstract
An output buffer driver calibration circuit and method are disclosed. Pull-up and pull-down devices of the output buffer driver circuit are simultaneously driven and the resulting output voltage is compared to a predetermined reference voltage, and a control signal is generated which is used to adjust the strength of one of the pull-up and pull-down devices so that the drive strength of the two devices approaches equality.
Claims88
A method of calibrating a driver circuit having pull-up and pull-down devices, said method comprising:
- simultaneously driving said pull-up and pull-down devices to provide an output voltage;
- comparing said output voltage with a reference voltage and providing a control signal representing the result of said comparison;
- and
- using first control signal to adjust the driving strength of at least one of said pull-up and pull-down devices of said driver circuit.
An apparatus for calibrating a driver circuit having pull-up and pull-down devices, said apparatus comprising:
- a circuit for comparing an output voltage, produced by said driver circuit when said pull-up and pull-down devices are simultaneously driven, with a reference voltage, and providing a first control signal representing the result of the comparison;
- and
- a circuit, responsive to said control signal, for adjusting the drive strength of at least one of said pull-up and pull-down devices.
A processor based system comprising:
- a processor;
- and
- at least one device for electrically communicating with said processor over a bus;
- at least one of said processor and device including an output buffer driver circuit coupled to said bus for providing an output voltage to said bus;
- and
- a circuit for calibrating said output buffer driver circuit, said calibration circuit comprising:
- a circuit for comparing an output voltage, produced by said driver circuit when said pull-up and pull-down devices are simultaneously driven, with a reference voltage, and providing a first control signal representing the result of the comparison;
- and
- a circuit, responsive to said control signal, for adjusting the drive strength of at least one of said pull-up and pull-down devices.
Dependencies are inferred from the claim text.