Complementary Metal Oxide Silicon Off-Chip Driver With Electrostatic Discharge Protection
Original Publication Date: 1989-May-01
Included in the Prior Art Database: 2005-Jan-27
By using one channel of a multiple channel p-type pull-up transistor to bypass output impedance matching resistors, a direct path for electrostatic discharge is formed from a driver output line to the high voltage supply (VDD). This low resistance path to VDD, in addition to low resistance paths to ground provided by existing protect diodes in downstream circuits, results in improved electrostatic discharge (ESD) protection of off-chip driver (OCD) circuits. Referring to the figure, output A from the main portion 2 of a complementary metal oxide silicon (CMOS) OCD circuit is connected to the gate of multiple channel n-type pull-down transistor Tn. All channels of the multiple channel device Tn are connected from impedance matching, pull-down resistor Rdn to ground. Therefor, transistor Tn is shown as a single device.