If a single ferrite bead is used it is not usually necessary to also have the separate beads as shown in Figure 8
Yup, it's probably cheaper to put a few small ferrite beads on the board than to put a big one on the cable.
Being a differential signal, I never understood why USB cables would _need_ them, but seeing it on a premium cable inspires the feeling that you bought a better product? I also think reduced 900MHz interference from cordless phones (remember those?) made homes quiet enough that the bead became more of a value-add for most applications. Just guessing...
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These seem to have become much less common. I'm guessing better filtering in devices themselves and possibly better cable construction?
From https://www.ti.com/sc/docs/apps/msp/intrface/usb/emitest.pdf :
Yup, it's probably cheaper to put a few small ferrite beads on the board than to put a big one on the cable.
Being a differential signal, I never understood why USB cables would _need_ them, but seeing it on a premium cable inspires the feeling that you bought a better product? I also think reduced 900MHz interference from cordless phones (remember those?) made homes quiet enough that the bead became more of a value-add for most applications. Just guessing...