So I was designing a front end for a 16bit ADC and had settled on a design and preliminary values. I decided to google around and see if any other designs could help me make things better when I stumbled upon a project that used the exact same parts with the exact same intent but with different descrete values.

This project I found was for an old product from 2004 that the company had open sourced the hardware for but previously it was closed source.

My question is simple. When you are designing something and it is very close to a competitors design and you are both using that design for the same purpose, are you liable for intilectual property infringement? I do not want to design something and start selling it to find out a year later bigOrg LTD. Holds IP rights on that "style & usage" of said part and I owe them $5M...

This might not seem to happen that often but I have run into it twice so far. I designed a logic analizer and to scale the unknown 0-7V input into the TTL range of my buffer I made a 1M/5M/1M divider between 5V and GND, input with a 330ohm resistor and 10pf cap to my buffer. I got to these values using spice and making a way to really ram in a logic change without going over specs. About 6 months later my buddy sent me a hack on the ZeroPlus Logic Cube and they use that exact layout with only two resistors of different value.

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    \$\begingroup\$ What country's laws? I see that you are in Canada. \$\endgroup\$ – Brian Carlton Sep 13 '11 at 16:44
  • \$\begingroup\$ @Brian Canada and United States are my primary concerns \$\endgroup\$ – uMinded Sep 13 '11 at 21:14

I Am Not A Lawyer, but...

the usual run of intellectual property divides into these areas:

  • patents (government-granted monopoly of a method or system for accomplishing particular functions that are non-obvious, useful, and novel)
  • copyrights (right to prevent others from using identical design elements)
  • trademarks (government-registered brand names / logos)
  • trade secrets (ideas kept secret, no legal protection here)

Unless you have a patent on a particular functional piece of circuitry, or you can prove that someone else made an effort to copy widespread portions of your schematic/layout/software, it would be difficult to keep someone else from using similar circuit elements. (And the same for them to prevent you from doing so.)

Resistor dividers + capacitors probably don't meet either criterion (although the US Patent Office has granted patents for things that are more obvious), so I wouldn't worry about it.

If you're talking about more complex ideas, you should probably talk to an attorney who specializes in intellectual property law.


In the US:

  • Copying their PCB layout is copyright violation. Re-draw your own layout from the schematic, even if the components end up in the same place (which is often necessary to make things work right).
  • Copying their circuit, however, is lawful reverse-engineering, so it's fine. If they want to prevent people from copying their circuit, they need to patent it. http://en.wikipedia.org/wiki/Reverse_engineering#Legality
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    \$\begingroup\$ "Copying their circuit, however, is lawful reverse-engineering" In my jurisdictioon (Netherlands) that is definitely not true. Or rather: you can reverse-engineer to your hearts content, but you are not allowed to produce exact copies. Copyright infringement. \$\endgroup\$ – Wouter van Ooijen Sep 13 '11 at 20:56
  • \$\begingroup\$ @endolith "allows reverse engineering for the purposes of interoperability, but prohibits it for the purposes of creating a competing product, and also prohibits the public release of information obtained through reverse engineering" You can do it to lean from but not compete with. I have seen companies xray pcb's and reverse draw schematics. In my case if I use the same components the schematic would only be very similar (different discretes) and the PCB would be different as I lay out myself. \$\endgroup\$ – uMinded Sep 13 '11 at 21:19
  • \$\begingroup\$ @uMinded: That's in the EU, though \$\endgroup\$ – endolith Sep 14 '11 at 2:09

Legal questions are alwas troublesome (or rather, the answers are).

Although the big picture is global, the nitty gritty details differ a lot from country to country (USA: state to state??). When you have decided on your jurisdiction, you will find out that a lot of things are not that clearly expressed in law, and a lot depends on court rulings, which often surprise even the specialists. And sadly a lot of interesting cases are settled out of court and under non-disclosure, creating "invisible law" :(

When you design something "from fresh" (without knowledge of the competitors product) you will generally not have to worry about copyright law, because that is about copying of a relalization rather than an idea. (not 'generally'...) But when you take something obtained from someone else and copy it verbatim, you might well be in trouble.

Patent law is a different beast, because it protects (or can protect) more broad ideas rather than a specific implementation. The positive side is that you can't patent something that is not new. Or rather, that is the theory... And you might come up with something that is not new now, only to discover (in court) that someone has patented it 20 years ago.

But patent lawsuits are costly affairs, so the big players genrally won't hurt you unless you are big too, in which case you probably have a legal department.

  • \$\begingroup\$ IP and Patents are quite vague in the law on purpose I think... Funny example of what brought this up: I was making a USB oscilloscope for fun and had drawn out a block diagram and chosen components based purely off of specs then price. I then found out that Bitscope used on a retired product the exact same op-amps, ADC, analog switches as I had sourced and had them connected in the exact same way I had planned. Made me think as obviously they got to the parts the same way I did. And you can only hook up an ADC in so many ways... \$\endgroup\$ – uMinded Sep 13 '11 at 21:24
  • \$\begingroup\$ For this case I would guess that the solution both you and they choose was an obvious one ('obvious to a skilled engineer', so not patentable, at least not now), and found independently (hence not 'slavisly copied', so not covered by copyright). But nothing can protect you from patents that were filed 10 or 20 years ago, or from patents that are filed now but should never be accepted because they are state of the art. \$\endgroup\$ – Wouter van Ooijen Sep 13 '11 at 21:37

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