Gate coupled SCR for ESD protection circuits

US5907462A · kind A · utility

Assignee

• TEXAS INSTRUMENTS INCORPORATED · US

Inventors

• Amitava Chatterjee · Plano, US
• Charvaka Duvvury · Plano, US
• Ping Yang · Richardson, US
• Ekanayake A. Amerasekera · Plano, US

Key dates

• Filing date: Sep 7, 1994
• Grant date: May 25, 1999
• Expiry date: Sep 7, 2014

Classification

• Technology area (CPC H): Electricity
• CPC primary: H10D8/80

Abstract

A protection device comprising a gate-coupled silicon-controlled rectifier (SCR) (100), SCR (100) comprises an anode (105) formed in n-well (104) and connected to a pad (128) and a cathode (111) connected to ground. A gate-coupled NMOS transistor (120) has a gate (116) connected through a resistive element (118) to ground. A n+ region (112) forms both the cathode (111) and a source of the NMOS transistor (120). N-well (104) forms the drain. Stress voltage is coupled from pad (128) to gate electrode (116) causing NMOS transistor (120) to conduct. This, in turn, triggers SCR (100) which dissipates the stress current at the pad (128). The coupled voltage at gate electrode (116) dissipates within a designed time constant through resistive element (118).