From: Geoff Hall [g.hall@ic.ac.uk]
Sent: 16 July 2002
19:45
To: Brown, RM (Bob) - PPD
Cc: Peter Sharp (E-mail);
Philippe Bloch (E-mail); Cockerill, DJA (David) ; Bell, KW (Ken) ; Greenhalgh,
RJS (Justin) ; Lodge, AB (Tony)
Subject: Re: Input protection
Hi
Bob
Peter may wish to add to this but at the FPPA review in January,
information was presented on the ESD protection performance of the circuit
(attached). The input is AC coupled via a hefty capacitor which is supposed to
be specified for the APD at least, and this should be part of the system spec
(as opposed to the amplifier spec).
For a 0.25um amplifier, this will
probably have to be handled somewhat differently than in the FPPA, although the
decoupling capacitor will obviously still be present. We are aware of the issue.
I do not recall seeing a specification of the protection requirement, (ie
transient charge, current, etc), except on the assumption that typical ESD
protection would suffice (eg see FPPA spec and below). If you have otherwise
defined requirements, we can compare our expectations with them at the
appropriate point.
I agree it would be a good idea to verify this with a
VPT and I'm not sure if you can already do it with the present version of the
FPPA (ie if ESD protection was in.) If not then it should be possible with the
new version once it returns. I don't know if it's been checked with APDs
either.
cheers, Geoff
In case the ESD spec is not familiar, here
is the official version. (Peter D aims for 1500V).
7.1.1.
Human Body Model Sensitivity:
/smaller>A source of ESD damage
is the charged human body, as modeled by HBM standards. This testing
model
represents the discharge from the fingertip of a standing individual delivered
to the conductive
leads of the device. It is modeled by a 100 pF capacitor
discharged through a switching component and
1,500 ohm series resistor into
the device under test. The discharge itself is a double exponential
waveform
with a rise time of 2-10 nanoseconds and a pulse duration of approximately 150
nanoseconds.
The use of a 1,500 ohm series resistor means this model
approximates a current source. All devices
should be considered as HBM
sensitive. The HBM ESD sensitivity of devices may be determined by
testing
the device using one of the referenced test methods. HBM sensitivities can be
found in RAC
VZAP, Qualified Manufacturers, List of Products (QML-19500) or
Qualified Manufacturer List
(QML-
38535).
/smaller>