Patent Number: 6,294,924

Title: Dynamic termination logic driver with improved slew rate control

Abstract: A dynamic termination logic driver, the driver capable of launching signals at a driving end of a transmission line and terminating signals at a receiver end of the transmission line, controls slew rate over a wide range of variations in operating conditions, manufacturing processes and output voltage levels. Such a driver also advantageously limits any crowbar current, thereby reducing the overall power consumption of the driver with little, if any, degradation of driver performance. The driver includes a pull up circuit having an impedance, the pull up circuit including a pull up output circuit and a buffer circuit, the pull up output circuit including a parallel pull up circuit, a pull up output control circuit, and a pull up slew rate control circuit, wherein the parallel pull up circuit and the pull up output control circuit are coupled in parallel. The driver also includes a pull down circuit having an impedance, the pull down circuit including at least one pull down output circuit, the at least one pull down output circuit including at least one pull down slew rate control circuit, a parallel pull down circuit and a pull down output control circuit, wherein the parallel pull down circuit and the pull down output control circuit are coupled in parallel. The driver also includes a plurality of output elements within the pull up circuit and the pull down circuit, wherein the plurality of output elements are selectively enabled and disabled with a controlled slew rate. The selective enabling and disabling is based on an impedance control code.

Inventors: Ang; Michael A. (San Francisco, CA), Taylor; Alexander D. (Olga, WA), Starr; Jonathan E. (Cupertino, CA), Vishwanthaiah; Sai V. (Sunnyvale, CA)

Assignee: Sun Microsystems, Inc.

International Classification: H03K 19/00 (20060101); H03K 19/003 (20060101); H03K 019/018 ()

Expiration Date: 09/25/2018