Question Why do the wires have to be on the shorter side when relocating the Bluetooth/Wifi board?

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I can understand why the wires would need to be the same length. But I don't get why the wires would need to be short in length, or what "short" even means since the word is relative by definition. Especially since both the Bluetooth and Wifi modules are normally located at the other side of the board.
 

jefflongo

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The traces for WiFi and Bluetooth are relatively high speed, and as such require certain considerations as they are routed on the PCB. You mentioned length matching, which is one of those considerations. Other considerations are trace length and impedance. On the PCB, the traces can be relatively long because they are impedance matched along the PCB. When we decide to solder wires directly to the PCB, we are basically foregoing all of these design considerations.

We attempt to maintain the signal integrity by keeping wires short and twisting differentially paired signals. The longer your wires are, the worse the signal integrity gets (which matters for high speed signals). There is no definition of "short" because ideally we wouldn't be soldering wires and messing up the signal integrity in the first place. You just want them to be as short as possible. How short is short enough that it doesn't stop working? It's hard to say.
 
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