ibis model for THS3201

Hello Liu,
I am checking on this for you. Please give me a day or 2 to find an answer.
-Samir

Hi Samir,

Thanks a lot.

I really appreciate it.

Jason

Hi Samir,

How is it going?

Looking forward for your answer.

Thanks a lot.

Jason

Hello Jason,
I have emailed the Design toold dept. regarding your question and am waiting to hear back from them. I will ping them again today for a response. sorry for the delay.
-samir

Hi Samir,

I really appreciate your help.

My project right now stuck on the simulation part，so i am kind of anxious of the model.

Thanks a lot.

Look forward  for your answer.

Jason.

Jason,

I think this question is more suitable for the software vendor. Our experience with signal integrity simulation is with Mentor HyperLynx only.

Here's a reference I found: http://emlab.uiuc.edu/jose/Theses/Kuo.pdf. Page 36 talks about simulation models, please take a look.

Thanks,
JC

Hi JC,
Thanks for your reply.
I checked that before.
The models i can use in ALLEGRO PCB SI is IBIS model or the DML file transfered from the IBIS model.
What is the model used in Mentor HyperLynx? Can SPICE model directly work in there?

Still look forward for the answer from Samir.

Thanks.
Jason

Hello James,
I had referred your question to JC as he is the expert on Spice and CAD tools.

Hi Samir,

Thanks for your help.

Still look forward for the answer.

Jason

Hi Samir & JC,
Do you have the gerber files for the THS3201 evaluation board?
I didn't find it on the webpage.
Can you give one copy of that?

Also, i am trying use spice to ibis converter to get the IBIS model for THS3201. But it always has some problem.

I don't know if it is the converter's problem or it's an analog chip model.

Thanks.
Jason

Jason, Here are the gerber files. I do not know about Spice to IBIS conversion so unfirtunately cannot help you there.

THS3201DGN_Gerber.zip

Hi Samir,

Thanks a lot for the gerber files.

But i can't open it with cadence pcb editor, protel or cam. 

Can you tell me what software are you using for the gerber file or how i can open them?

Again hope get the ibis model for the ths3201.

Thanks.

Jason

Hello Jason, We use Gerbtool to view the gerber files:
http://www.wssi.com/index.php?option=com_content&task=section&id=16&Itemid=167
Also, with regards to the IBIS model I do not have any suggestions. We really dont do IBIS models for amplifiers as the applications are analog centric.
-Samir

Hi Samir,
Thanks for the answer.
I understand the reason why it does not have the IBIS model because of the analog centric.
When you guys design the board like the evaluation board for it, you would do the simulation for the PCB design.
What do you guys do? Can you give some advice of that?

Thanks.
Jason

Hi Samir,

Another quick question is there are two NC pins on the THS3201(pin1 and pin8).

But on the evaluation board, these two pins are connected to PD_REF(J8) and /PD(J9).

What are these two used for? On the datasheet it said it is not internal connected.

Thanks. 

Jason.

Hello Jason,
The reason the 2 pins are called PD_REF and /PD is because this board can also be used for other deviced that may have a Power Down function. Please disregard the markings on the board for this device. Since they are not internally connected they can be tied to either supply/GND/left floating.

Hi Samir,
Thanks for your answer.
Also, can you please advise how you guys do the PCB level for the analog chip like THS3201.
Since they don't have the IBIS model.
This is the 1st time to do a PCB simulation for an analog chip, so please advise.
Thanks a lot.
Jason

There are various tools available to estimate parasitics based on trace-length etc. For the most part I am extremely careful during layout and follow the guidelines as shown in Page 20 of the datasheet. I dont really use the amplifier to provide clocks so have never quite analyzed it this way.

Ok, thanks a lot for your help.
Jason.

Hello Jason,

Can you substitute a simple circuit into the simulation circuit?

The THS3201 non inverting pin can be modeled as a 780kOhm resistor to ground in parallel with a 1pF capacitor. If you are using a termination resistor this can be added in parallel as well and it should dominate the performance up to very high frequencies.

Are you using the inverting input? Because it's current feedback it will have a different impedance than the non inverting input. Normally, the feedback network is all that is connected to the inverting input.

Regards,
Loren

Hi Loren, 

Thanks for your reply.

My design is to send signal to non-inverting pin while add feedback circuit back to inverting pin, the gain is 10.  

I guess i can use the 780k // 1pf as the input  part for the simulation.

Any idea on the output and feedback circuit for the simulation? 

Thanks a lot.

Jason

Hi Jason,

No, I don't have any idea on the output or feedback. I do not know how IBIS models work for outputs. You could probably use an ideal source set up for a 0.7/0.9 ns rise / fall time and 0.01 Ohm output impedance. I know how to do this in SPICE, but I have not used the tool you are using, so it is hard for me to know.

Another option is to set up your circuit in TINA-TI using the spice model and then create a signal source that produces the same waveform in your tool.

Regards,
Loren

Hi Loren,

Thanks for your reply and suggestion.

I will try them.

Jason