I wouldn’t worry too much about the impedance not being exact, expecially if the tracks are fairly short, and you are not running at the full USB 2.0 speeds. There are plently of commercial products that have USB, and only use a double-layer PCB.
I wouldn’t worry too much about the impedance not being exact, expecially if the tracks are fairly short, and you are not running at the full USB 2.0 speeds. There are plently of commercial products that have USB, and only use a double-layer PCB.