Simulation software for people moving into high speed (>200Mhz) pcb traces - Page 1
Forum section: electronics / beginners

author: RidiculousRichard
author_rank: Newbie
timestamp: July 16, 2012, 10:23:53 pm
content: Hi,There is a good starting point in the thread below for beginners to high speed design:https://www.eevblog.com/forum/microcontrollers/tutorial-on-microprocessormemory-track-length-erc/msg108158/#msg108158I was hoping the experienced members could recommend any em simulation software for modelling high speed impedance match pcb transmission lines to help the beginner (namely me) to such high speed designs.While there are simple free pcb trace designs (e.g. EEWebhttp://www.eeweb.com/toolbox/microstrip-impedance) they tend to leave off basic situations I am interested in (eg tightly coupled differential signal pair for a low cost 2 layer PCB, i.e. thick dialetric, using guarding ground traces to lower trace impedance and a naive attempt to cut cross-talk without using too much space)There are expensive software solutions that would allow the beginner to conduct quantified 'thought' experiments (Hyperlynx or microwave office) but they are generally out of reach of a hobbyist (my wallet is not looking to loose lots of weight!)Thank you all for your any suggestions or help you can provide,Richard(usually ending up looking rather ridiculous)

author: Short Circuit
author_rank: Frequent Contributor
timestamp: July 16, 2012, 10:47:58 pm
content: http://saturnpcb.com/pcb_toolkit.htm

author: Lukas
author_rank: Frequent Contributor
timestamp: July 16, 2012, 11:12:04 pm
content: Take a look at qucs. Besides normal SPICE stuff, it does also RF stuff such as microstrips.

author: jahonen
author_rank: Super Contributor
timestamp: July 17, 2012, 06:58:40 am
content: For true field solver, try Sonnet lite:http://www.sonnetsoftware.com/products/lite/Regards,Janne

author: free_electron
author_rank: Super Contributor
timestamp: July 17, 2012, 02:52:23 pm
content: What are you trying to solve ? Emc ? Emi ? Or signalintegrity ?When doing a board thr signalintegrity is issue number one. Corrupt the signal and the system will not work...Emi : immunity. Expose system to an electromagnetic field and see if it screws up. Like putting a cellphone that sends its 'chirp' close to an audio amplifier. Prut , prut, prut, peeeeeeeeer ,prut prut.. You know the sound. That is emi... You are not immune to the cell phones electromagnetic garbage.Emc : see if your system does not produce any garbage.... That causes prut prut in other systems.Now, the golden number is 3.. Anthing that is further than 3x away does not couple ...A 6 mil wide trace does not couple beyond 18 mils deep... For a standard double sided board the thickness is 62 mils... So kiss that goodbye. No microstrips there.... Unless your traces become 60 mils wide....Track to track you are side looking. Copper thickness comes into play.

author: RidiculousRichard
author_rank: Newbie
timestamp: July 19, 2012, 11:57:07 am
content: Thank you everyone for the help. I hope this thread also helps a budding beginner (I've never see one of them before)My own personal focus is signal integrity (and yes I was looking a 50-60mil tracks and thinking 'Oh Darnation, how will ever will I fit it in')Thanks again,Richard

author: jahonen
author_rank: Super Contributor
timestamp: July 19, 2012, 12:08:45 pm
content: Quote from: RidiculousRichard on July 19, 2012, 11:57:07 amMy honest advice is to use a multilayer board, it is much easier to do properly if you don't have a knife on your throat for costs.Especially so if you are beginner. For example, typical dielectric thickness might be 180 µm between 1st and 2nd layers, making nice 50-60 ohm microstrips a breeze (50 ohm trace would be about 300 µm wide in that case). Bus operating at such frequency (or more importantly, with signals with much less than 5 ns edge rate), it is pretty much mandatory. Trying to squeeze it on a two-layer board is one of those "look ma, no hands!"-stuffRegards,Janne