Dynamic impedance control for input/output buffers
AssigneeConversant Intellectual Property Management Inc.
InventorBruce MILLAR
Life of this patent
Estimating the term…
Abstract
A system and method of performing off chip drive (OCD) and on-die termination (ODT) are provided. A common pull-up network composed of transistors and a common pull-down network composed of transistors are employed to implement both of these functions. In drive mode, the pull-up network is configured to produce a calibrated drive impedance when an “on” output is to be generated, and the pull-up network is configured to produce a calibrated drive impedance when an “off” output is to be generated. In termination mode, the pull-up network and the pull-down network are configured to produce a calibrated pull-up resistance and pull-down resistance respectively such that together, they form a split termination.
Claims8
(canceled)
A memory device comprising:
- a first plurality of transistors connected in parallel between a first power supply and a data output terminal;
- a first plurality of Off-Chip Drive (OCD) configuration bits;
- a first plurality of On-Die Termination (ODT) configuration bits;
- logic for driving a gate of each of the first plurality of transistors based on the OCD and ODT configuration bits,
- the logic being configurable in an OCD mode to drive the gate of each of the first plurality of transistors based on a state of a respective one of the first plurality of OCD configuration bits to generate a first OCD impedance, and
- the logic being configurable in an ODT mode to drive the gate of each of the first plurality of transistors based on a state of a respective one of the first plurality of ODT configuration bits to generate a first ODT impedance;
- a termination enable signal to enable/disable the first ODT impedance when the memory device is not in the OCD mode;
- and
- a pad coupled to an external reference resistor (RZQ), the pad configured to be utilized for performing a calibration operation to calibrate the first OCD impedance and the first ODT impedance against an impedance reference of the external reference resistor.
Dependencies are inferred from the claim text.