Re: [IBIS-Users] Ccomp extraction via Tank method

Hi Lynne,

Too good to be true, in other words?
Thank You for the clarification, I'll then revert to doing things the 
old way, as you recommend.

Best regards,  Lars


Lynne D. Green wrote:
> Hi, Lars,
> 
> There have been several papers on C_comp extraction at the IBIS summits.
> They note that C_comp depends on both bias voltage and frequency, so it is
> impossible to extract a "single" value using this method.
> 
> The preferred approach is to make a linear fit to a ramp voltage response
> (ramp voltage at full-logic-swing; I=C*dv/dt=constant=linear fit).  This is
> close to what the I/O will see in an actual PCB.
> 
> Best regards,
> Lynne
> 
> 
> "IBIS training when you need it, where you need it."
> 
> Dr. Lynne Green
> Green Streak Programs
> http://www.greenstreakprograms.com
> 425-788-0412
> lgreen22@mindspring.com
> 
> 
> -----Original Message-----
> From: owner-ibis-users@eda.org [mailto:owner-ibis-users@eda.org] On Behalf
> Of Lance Wang
> Sent: Thursday, March 12, 2009 12:52 PM
> To: 'Lars Snith'
> Cc: ibis-users@eda.org
> Subject: RE: [IBIS-Users] Ccomp extraction via Tank method
> 
> Hi, Lars,
> 
> I would suggest you to try a larger swing for Vdc. Sometimes, in certain Vdc
> range, c_comp may not change significantly. 
> 
> Also, you can post your test case and results to the reflector or send to
> me. I am interested to find out.
> 
> Regards,
> 
> Lance Wang
> 978-764-2298
> IO Methodology Inc.
> 
> 
> -----Original Message-----
> From: owner-ibis-users@server.eda.org
> [mailto:owner-ibis-users@server.eda.org] On Behalf Of Lars Snith
> Sent: Thursday, March 12, 2009 1:15 PM
> To: Lance Wang
> Cc: ibis-users@server.eda.org
> Subject: Re: [IBIS-Users] Ccomp extraction via Tank method
> 
> Hello Lance,
> 
> Yes, by varying the DC component of the AC source in alter statements:
> Vsw Sweep2 gnd dcoffset AC
> 
> Best regards,  Lars
> 
> Lance Wang wrote:
>> Hi, Lars,
>> Did you change Vdc value?
>>
>> Lance Wang
>> 978-764-2298
>> IO Methodology Inc.
>>
>>
>> -----Original Message-----
>> From: owner-ibis-users@server.eda.org
>> [mailto:owner-ibis-users@server.eda.org] On Behalf Of Lars Snith
>> Sent: Thursday, March 12, 2009 11:29 AM
>> To: ibis-users@server.eda.org
>> Subject: [IBIS-Users] Ccomp extraction via Tank method
>>
>> Hello All,
>>
>> For Ccomp extraction I have so far relied on Time Domain methods. But 
>> as shown in the documentation (link below) the result is not always
>> reliable.   http://www.eda.org/ibis/summits/jun02/hegazy.pdf
>>
>> I have put together a simple testbench to play around with the Tank 
>> method, and true enough values are not especially sensible to any of 
>> supply, temperature or even process variations.
>>
>> However, before I embark on wrapping up a new flow for myself I 
>> thought I'd just ask this forum if there is already a recommended 
>> testbench for the Tank method out there? If so, I'd be most interested to
> share.
>>
>> Best regards,  Lars


-- 
Those who can, Do
Those who can't, Simulate

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