Simulation models  - Page 1
Forum section: electronics / beginners

author: joniengr081
author_rank: Regular Contributor
timestamp: July 27, 2023, 09:40:00 am
content: Hi, I normally use LT SPICE by Analog in which I can simulate an analog circuit using SPICE model.What are the IBIS models and how they differ from SPICE models ?And how the digital ICs can be added in circuit simulation.

author: tggzzz
author_rank: Super Contributor
timestamp: July 27, 2023, 10:05:33 am
content: https://duckduckgo.com/?q=IBIS+models

author: joniengr081
author_rank: Regular Contributor
timestamp: July 27, 2023, 10:20:41 am
content: I just notice that amplifiers normally have SPICE models while ADC and clock drivers have IBIS models. Does it means that SPICE models is for analog circuit simulation while IBIS is for digital ICs, if yes can we also have IBIS model for Microcontrollers and FPGAs ?

author: tggzzz
author_rank: Super Contributor
timestamp: July 27, 2023, 10:29:07 am
content: Quote from: joniengr081 on July 27, 2023, 10:20:41 amNo, and yes, respectively.In case you are incapable of using the search engine link I gave, have a look athttps://en.wikipedia.org/wiki/Input/output_Buffer_Information_Specificationhttp://emlab.uiuc.edu/ece546/appnotes/arpad.pdfhttps://www.analog.com/en/analog-dialogue/articles/ibis-modeling-part-1-why-ibis-modeling-is-critical-to-the-success-of-your-design.htmlThere's no point in our spending our life tobadlysummarise that information

author: joniengr081
author_rank: Regular Contributor
timestamp: July 27, 2023, 11:08:49 am
content: IBIS models are behavioral models which does not require schematic or circuit level information.SPICE models contains schematic ad circuit information.Does this means that we can get IBIS models for all types of analog and digital devices ? and also the SPICE model is only for simulating analog components in schematic ?

author: tggzzz
author_rank: Super Contributor
timestamp: July 27, 2023, 11:36:05 am
content: Quote from: joniengr081 on July 27, 2023, 11:08:49 amIBIS models are Spice models. Open up an IBIS file and look. (If a manufacturer has encrypted the contents, find another manufacturer/model)The only digital circuits you are likely to encounter are photon counting and femto-amp circuits.All other circuits are analogue. In particular "digital ics" are actually analogue ics whichinterpretanalogue voltages/currents as digital signals. For example, classic TTL ics inputs interpret any voltage above 2V as being a digital high, and less than 0.8V as being a digital low. Between 0.8V and 2V (and <0V, >Vcc) they are neither high nor low.Understanding that is a pre-requisite to understanding why "signal integrity" is such an important topic - and hence why IBIS models exist.

author: Terry Bites
author_rank: Super Contributor
timestamp: July 27, 2023, 12:46:03 pm
content: You can regard IBIS model is like a giant macro.

author: joniengr081
author_rank: Regular Contributor
timestamp: July 27, 2023, 12:58:46 pm
content: Yes, but these IBIS models are used in signal integrity analysis tools like Mentor Graphics Hyperlynx. I guess SPICE models can be used in such signal integrity simulation tools, right?

author: tggzzz
author_rank: Super Contributor
timestamp: July 27, 2023, 03:03:03 pm
content: Quote from: joniengr081 on July 27, 2023, 12:58:46 pmWhy "but"?I've no ideal what is in a Mental Graphics product; the last time I avoided using one was 30 years ago.MicroCap 12 (free as in beer since the creator retired) can use IBIS models.https://archive.org/details/mc12cd_202110