# Depicting Analog Signal Paths graphically

Is there a 'standard' way to depict analog signal pathways / chains that's simple, concise, and not too mathematical?

I've been searching online, but can't seem to figure out what such a diagram is called or any tools to make them. The diagrams I see are either full schematics or very high level block diagrams.

I'm thinking about, I think, the kind of diagrams used to depict control systems. What I'd like to do is draw similar diagrams to provide a quick reference to what the overall circuit does. I don't need it to contain electrical information as such, in that it isn't important that it should be compatible with Spice / similar.

An example set of symbols I'd need would be :

• A representation for inputs (single ended and differential)
• A representation for gain stages, showing gain information.
• Nicer if I can show the signal level before and after the gain stage, as well
• A representation for filters, showing cutoff frequencies
• A representation of simple feedback loops (say adders or subtractors)
• Perhaps a representation of instrumentation amplifiers (with transfer function Vref + G * (In+ - In-), as opposed to G * In for a simple gain stage)

Any clues about how to go about drawing these would be nice. Specifically, the following are questions that I think would help :

• What would such a diagram be called? Bonus if the name is something that is Google-able.
• Are there any tools (preferably free, open source, but I'll take something commercial as a reasonable starting point) available that can help quickly draw these things.
• Else, how is such information (number of gain / filter stages, expected signal amplitudes through the signal chain, signal shapes / frequencies / amplitudes, etc) effectively communicated.
• You can put as much detail into a block diagram as you want. – The Photon Feb 28 '15 at 19:49
• @ThePhoton True. I could draw each stage manually with, say, Dia. However, this doesn't make use of 'standard' recognizable symbols and representations - and consequently, making it readable for a sufficiently complex signal chain would be tough. Secondly, maintenance will be a nightmare. Something along the lines of what UML is for software would be preferable to a page full of text-filled boxes. – Chintalagiri Shashank Feb 28 '15 at 19:53
• You don't consider the relevant xkcd to be an adequate model for such diagrams? – The Photon Mar 1 '15 at 2:40