A USB 3.0 PHY includes a SuperSpeed PHY and USB 2.0 PHY. Both PHYs are configurable in the HX3. HX3 SuperSpeed PHY can be configured to improve USB 3.0 signal quality by changing transmit amplitude, or commonly known output swing and the de-emphasis which is the amount of decrease in low frequency content of the transmitted signal. Both provide effective compensation to reduce crosstalk and to correct USB 3.0 signal distortion over a lossy channel. The two SuperSpeed eye diagrams shown on this page illustrate the signal quality improvement realized by these adjustments. The eye diagram on the left is a HX3 downstream port using the default PHY settings. Although the eye height (i.e., the vertical opening of the Super Speed eye) at 118 mv is more than the USB specification minimum value of 100 mv, the narrow opening provides only a small margin for passing USB compliance. By boosting the upper swing of the PHY by 20% using transmit amplitude adjustment, the eye height is increased to 142 mV which provides much more margin for passing USB compliance.