CML (current mode logic) OCD (off chip driver)—ODT (on die termination) circuit for bidirectional data transmission

US6847225B2 · kind B2 · utility

Assignee

• Infineon Technologies AG · DE

Inventors

• Hans-Heinrich Viehmann · Munich, DE
• Stefan Lammers · Hersbruck, DE

Key dates

• Filing date: Mar 21, 2003
• Grant date: Jan 25, 2005
• Expiry date: Mar 21, 2023

Classification

• Technology area (CPC H): Electricity
• CPC primary: H04L25/0294
• WIPO field: Digital communication
• WIPO sector: Electrical engineering

Abstract

An apparatus for use as both an off chip driver (OCD) and an on die termination (ODT) circuits. A preferred embodiment comprises a control circuit (for example, control circuit 305) coupled to a dual function OCD/ODT circuit (for example, OCD/ODT circuit 330) with an enable line coupled to the control circuit. The control circuit may be used to selectively choose OCD and ODT functionality based on a value on the enable line. With the control circuit choosing OCD, the dual function OCD/ODT circuit functions as an OCD circuit, placing signals provided through the control circuit onto a transmission line. With the control circuit choosing ODT, the dual function OCD/ODT circuit becomes terminating resistors for incoming signals on a transmission line. The use of a single circuit for both OCD and ODT functions can save both integrated circuit real-estate and implementation costs due to a reduction in use of circuit elements.