Re: [IBIS-Users] Modeling Diff Buffers

Hi Sudharshan,

Thanks a lot for your response!

1 & 2) I tried searching for the keywords in cook book but in vain.Could 
you help me point to the docs/pdfs where I can get all these special 
keywords.

3)  I followed sec 4.7 of IBIS cook book to generate the C-Comp for drivers
1. Vary P,V (voltage input to data in), T
2.  Find the max and min and add them to tables
3. Avg becomes the typ for C-comp

Should I change this methodology?

Once again thanks for your inputs!

Thanks,
Anguraj

Sudarshan Honnudike wrote:

>
> Hi Anguraj,
>
> I asked similar questions sometime back, but even I didnt get the 
> answers. I will try to answer to your first 2 questions
> based on my experience.
>
> 1. Vdiff value can also be specified under [Receiver Thresholds] 
> keyword. So if you have, say 2 speed modes of operation
> you need to have two [Model]'s for those 2 modes. As these two modes 
> will have separate [Receiver Thresholds] section
> you can define 2 separate Vdiff under these 2 modes. The corresponding 
> parameter to define Vdiff under [Receiver Thresholds] keyword is
>
> Vdiff_ac =
>
> 2. Similarly Common mode range can be specified under [Receiver 
> Thresholds] keyword. The parameters corresponds to common mode
> range under  [Receiver Thresholds] is
>
> Vcross_low =
> Vcross_high =
>
> For the third question , what i can suggest you is, to check the value 
> what you are getting with the datasheet. That should confirm the 
> correctness.
> Normally we vary the process corner and voltage applied to get the 
> typ, min and max values of C_comp.
>
> Let me know if you find these answers helpful.
>
> Best Regards,
>
> Sudarshan HN
> NXP Semiconductors/CTO /PLT
> C-4, Manyata Tech Park, Nagawara
> Bangalore-560 045 , India.    
> Ph:+91-80-40267073  
> Fax: +91-80-4026 7855
> seri:sudarsha@inpsblr
> E-mail: sudarshan.honnudike@nxp.com
>
>
>
>
>
>
>
> Anguraj K <b05108@freescale.com>
>
> Sent by:
> owner-ibis-users@server.eda.org
>
> 2007-02-02 04:00 PM
>
> To
> ibis-users@server.eda.org
> cc
>
> Subject
> [IBIS-Users] Modeling Diff Buffers
> Classification
>
>
>
>
>
>
>
>
>
> Hi Experts,
> Could you please answer my below questions?
>
> 1. If vdiff value varies for diff pins (due to diff modes of operation,
> namely speed), How do I define that in IBIS models.
> Through [Diff Pin] keyword, we can pass only one value to vdiff.
>
> 2. How to define common mode value in the diff signals? (I believe there
> are other IBIS users who raised the same question some time earlier)
>
> 3. When measuring C-Comp for drivers,
> I see three main variables on which die cap depends on.
> 1. Freq of operation
> 2. Data value (0 to vdd) to be sent
> 3. Process corners
>
> I vary these three variables and finding the max and min value for
> C_comp. Is that right?
> But,  I usually see very huge die-cap for the drivers(unrealistic)
>
>
>
>
>
>
> -- 
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