FreeLists / si-list / [SI-LIST] Re: ESD solution on antenna output

[Raymond.Leung@xxxxxxxxxxx]

I cannot offer a direct solution too.  However, from the IC view point
usually there is a protection device in a IC input, which can turn on
within a couple of ns when under ESD stress.  For human body ESD
protection of 2000V spec., it can sink transient current up to 1.33A.
Therefore, if the slew rate of the surge is less than 2V/ns, and the
short circuit current is less than 1.33A (for 2000V spec), then I would
believe the ESD stress is under control.  I must say these figures are
for reference only, they vary across processes and designs.

Regards,
Raymond Leung





Raymond Anderson <Raymond.Anderson@xxxxxxx> on 06/02/2004 09:03:00

Please respond to Raymond.Anderson@xxxxxxx

To:   si-list@xxxxxxxxxxxxx
cc:    (bcc: Raymond Leung/sdc)

Subject:  [SI-LIST] Re: ESD solution on antenna output



Can't offer a solution, but it seems to me that the inductor will shunt DC
and low frequency stuff to ground and thus protect the antenna input device
from those sorts of impingements, however fast rise time / high
frequency ESD
stuff will still be able to develop a voltage across the inductor. In fact
real fast impulse type ESD spikes might even be worse due to an inductive
kickback mechanism. (At least it seems that way to me). Perhaps some
ESD experts can speak up.



-Ray Anderson
Sun Microsystems

Ian Barrett wrote:

> I am currently having a lively discussion with a colleague about an ESD
> problem we have encountered. The trouble is I don't think either of us
> know
> enough to be able to convince the other of our point of view.
>
> The product is a small radio transmitter that is very susceptible to
> an ESD
> spike applied directly to it's antenna. The design includes a small
> inductor
> between the antenna output and ground. My colleague (the designer) put it
> there to try and alleviate any potential ESD problems. I have found
> that I
> cannot solve the ESD susceptibility problem without removing it.
>
> He claims 'any ESD experts will tell you to place this inductor' and
> wants
> me to try and find another solution to the problem. But I think the
> inductor
> is making the situation worse by coupling the ESD spike onto the ground
> plane.
>
> Can anyone offer some theory to back up either argument?
>
> Ian.








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