The application of electronic product as visible, so of electronic product electrostatic defend in making electronic products plan, work indispensably. In the electronic product that has exterior interface, almost can ESD defends parts of an apparatus.

 

 

The systematic engineer that high speed circuit designs or what hardware engineer must choose the place in be being designed carefully to need is all yuan of parts of an apparatus, choose appropriate ESD to protect component to have bigger than before challenge sex, because ESD parts of an apparatus is on interface of circuit of a few high speed,becoming is a simple ESD parts of an apparatus no longer, still included the parasitism parameter of stray, and the parameter such as the parasitism inductance when installation arrives on PCB board. The ESD that pursueing left as follows is a model protects parts of an apparatus, right graph is the equivalent circuit graph that installation is in a on PCB board to simplify:

 

 

Apparent circuit becomes more complex. Here still does not have the IO capacitance of computational ESD parts of an apparatus. The IO parasitism capacitance that marks in the Datasheet that next graphs are some TVS canal:

 

 

The USB3.0 that Changshu is not to know with everybody below is example, the principle that builds to emulate in ADS pursues (the Example of use ADS can) :

 

 

Emulate acquisition eye figure to pursue as follows [] be shown:

 

 

 After the S parameter that adds a TVS canal that prevents ESD in original principle intent, principle graph pursues as follows be shown:

 

 

Other condition maintains with in front same, emulate acquisition eye figure to pursue as follows [] be shown:

 

 

Look from eye graph, both have apparent difference, observe its are measured again, apparent, when the model that brings canal of TVS of ESD parts of an apparatus, its result is poorer. Although result or the standard that accord with USB3.0 ask,be in in this article, but had become very poor, the result below the effect that if be in,provides without consideration TSV is very poor, so after adding TVS to be in charge of, can bring about the requirement that does not satisfy a design as a result very likely.

 

The S parameter that next graphs are parts of an apparatus of canal of a TVS:

 

Apparent, when signal rate is lower, its loss ratio is lesser, but the promotion as rate, apparent loss can greaten a lot of. Although at present a lot of companies cannot offer the S parameter of ESD parts of an apparatus, but to high speed circuit character, this is one of factor of influence that need a consideration really. When choosing parts of an apparatus so, want those who see parts of an apparatus to defend not just grade, still need to notice its place unripe effect.