Change USB signal polarity with inverter

[ctzof]

Hello,
Can I use 2 inverters to change the polarity of USB 2.0 differential pair signals?

 

[KlausST]

Hi,

no, because USB data lines are bidirectional.
And they need high Z and resistors for USB speed configuration.


Klaus

 

[ctzof]

Hi,

no, because USB data lines are bidirectional.
And they need high Z and resistors for USB speed configuration.


Klaus

Thanks you are right.....is there any way I can do that?

 

[FvM]

I don't believe that anyone wants to invert the USB bus signals. It's a 100 percent safe method to stop USB bus operation, so what should be the purpose?

 

[ctzof]

I don't believe that anyone wants to invert the USB bus signals. It's a 100 percent safe method to stop USB bus operation, so what should be the purpose?

I describe my problem in this post

https://www.edaboard.com/threads/320186/

 

[FvM]

You can't change polarity instead of swapping USB D+ and D- signals. USB signalling involves non-differential symbols like a "single-ende zero" (SE0), also specific DC levels on both lines to detect device speed and attachment. Forget about the idea and use a trace crossing with vias as anyone does.

 

[ctzof]

You can't change polarity instead of swapping USB D+ and D- signals. USB signalling involves non-differential symbols like a "single-ende zero" (SE0), also specific DC levels on both lines to detect device speed and attachment. Forget about the idea and use a trace crossing with vias as anyone does.

So this is not a problem I can route one of the signals to a different layer through a via. This doesn't affect the quality if the signal? The only think I should be careful is to keep the length of the lines the same I suppose.

 

[FvM]

So this is not a problem I can route one of the signals to a different layer through a via. This doesn't affect the quality if the signal? The only think I should be careful is to keep the length of the lines the same I suppose.

Of course a trace crossing with vias to a different layer affects signal integrity. But HS USB still involves moderate signal frequencies (compared to USB 3.0, PCIe or SATA).

The USB 2.0 cable specification allows for 100 ps intra pair delay skew which corresponds to about 15 mm PCB trace length.