When an inductor is printed on a PCB in the shape of a 'square wave' or square zigzag, each time it zags the trace doubles back on itself. Doesn't this cancel the magnetic field to an extent? How much does the coil structure matter to a coiled inductor, or would the straight wire have the same inductance?
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When it doubles back it'll reinforce the magnetic field, and only destructively interfere on the next line over (with the current going the same way).
But I have no clue how much difference it makes, or how much it acts like a straight wire of the same length.
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The ones you see on PC boards may be delay lines. When you route a differential pair and turn a corner or something, one trace gets longer than the other. So some people wigwag the shorter one to make the electrical lengths equal.
Like this:
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I doubt that a tight wigwag has a time delay that exactly corresponds to the geometric trace length that the PCB layout software reports.
Real RF inductors are usually proper spirals.
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John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com
Precision electronic instrumentation
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We make spiral coils on PCB to 'shim' magnetic fields. I'm not sure what you mean by zig-zagging back... maybe a picture?
Re: a coil versus a length of wire. You get more inductance from the coil. I think if you have a fixed length of wire and wanted to make the largest inductance then you'd wind it as one big single turn coil. (hopefully someone will correct me if that is wrong.)
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My liberal friends think I'm a conservative kook.
My conservative friends think I'm a liberal kook.
Why am I not happy that they have found common ground?
Tim Wescott, Communications, Control, Circuits & Software
http://www.wescottdesign.com
Oh yeah, you can make a choke. You can think of it as an inductor, or as a long, lossy, high-impedance transmission line, which it is in the sense that it has some limiting Zo at high frequencies, and reflections. Chop out some ground plane to increase Zo.
I did a zigzag choke like that recently:
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It maybe wasn't absolutely necessary, but I had the room and it was sort of fun.
Hey, engineers are easily amused.
If you know the operating frequency, you can optimize the length for max impedance. RF stuff.
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John Larkin Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com
Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators
Its operation depends on its magnetic field, so what is the effect of having each segment of conductor nearest to segments conducting in the opposite direction?
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