Quote:
Originally Posted by hooverphonique
Hi Stedy,
what do you mean by:
tightly coupled traces
?
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The spacing between tracks is close. With 1980s/1990s technology, to a large extent this is ok. Newer technologies from around 2000 onward this would cause issues as the signals are faster, this increases a phenomenon called cross talk, whereby adjacent, closely spaced signals interfere with each other. Adding power planes helps as it provides better impedance controls and changes the coupling mechanism slightly.
I consulted 'the book' (Art of Electronics 2nd edition from 1989) for PCB design, they talk about advanced layouts on 8mil/thou traces and 8 mil/thou spacing being mainstream technology. Modern PCB designs can use 4 thou/0.1mm trace width and separation, if the PCB technology and device technologies allow.
I'm glossing over a lot of PCB design stuff here, I left the other good book, no not the bible,
High speed digital design at work. This details the complexities in more detail.
One issue, that affects these old systems is when you add new expansions, with newer, faster, more power hungry electronics. They show up weaknesses in the existing design. These weaknesses were not really present when designed in 1992, they met the requirements of the day. For a modern design, the approach used would not be suitable.
I've been doing PCB designs for over 20 years, learnt a few things.
