A good explanation and example of a USB interface circuit?

 Every USB circuit I come across seems to be about the same with D- and D+ clamped to 3.6 volt with a zener diode. These wires are then passed to uC's io pins. Am I correct in thinking this setup doesn't take advantage of USB's differential signaling scheme? Because I thought an op-amp was needed for differential signaling. Does anyone know of a good resource, with circuit examples, that explains how USB transceivers work? I'm not interested in the actual protocol (NRZI, and all) I already understand most of that, what I'm really looking for is circuit level stuff.

lemonie7 years ago
You understand the protocol but not the silicon-switching - that's it?

hacim (author)  lemonie7 years ago
Let's just say I understand the protocol enough for my purposes.