A specific case of an SCR-based solution which can be used to develop a wide range of on-chip ESD protection circuits is the diode triggered SCR (DTSCR). As its name implies, a DTSCR is constructed by combining an SCR with diodes to form a versatile circuit whose properties can be tuned at will to suit the requirements of the IC/interface which needs to be protected.
Latch-up refers to unwanted short circuits which can occur in an integrated circuit whereby the power supply is inadvertently connected to the ground. In the first part (threat) of the article the focus was on the threat of latch-up and different ways to prevent it. In this part (opportunity) we discuss how (parasitic) SCR devices can be used in a positive way.
The conventional dual diode approach is used a lot as a simple ESD protection solution for all types of interfaces. However sometimes it causes issues.
Sofics’ 2017 EOS/ESD publication. This paper presents a novel approach to reduce the parasitic capacitive loading of RF and high speed digital interfaces by up to 35%. Unlike in the classic dual diode protection, both junctions connected to the pad are used in every stress combination.
Sofics’ 2008 RCJ publication.
The Silicon Controlled Rectifier (‘SCR’) is widely used for ESD protection due to its superior performance and clamping capabilities. However, many believe that SCR based ESD protection is prone to latch-up, competitive triggering, long development cycles and slow trigger speed. This paper provides an overview of the problems and corresponding design solutions available.