The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 02, 2019
Filed:
Apr. 27, 2018
Silicon Laboratories Inc., Austin, TX (US);
Yunfeng Xi, Georgetown, TX (US);
Jeremy C. Smith, Austin, TX (US);
Silicon Laboratories Inc., Austin, TX (US);
Abstract
A diode string for a semiconductor circuit configured with a guard ring silicon-controlled rectifier (SCR) for electrostatic discharge (ESD) protection. The diode string includes multiple NPN transistor diode structures formed in an N-well structure and electrically coupled in series between a reference voltage node and an I/O pad. Each diode structure may include a P-type retro-well structure including at least one N+ doped region and at least one P+ doped region. The P+ guard ring includes at least one P+ doped structure formed in the N-well structure disposed on either side of the first diode structure and electrically coupled to the reference voltage node. The P+ guard ring forms the SCR with the first diode structure. The diode string is triggered in response to an ESD event, which activates the SCR, and the SCR clamps the I/O pad to the reference voltage node and handles the ESD current.