高速走線注意事項

USB

1. Route USB D+ and D- signal pairs together with a consistent trace separation and 90-ohm differential impedance
   90歐差分阻抗
2. Route USB D+ and D- signal pairs using minimum vias and corners.
   最少的過孔和拐角
3. Route USB D+ and D- signal pairs over a ground layer
   要有完整的信號參考地
4. Use 20-mil minimum spacing between high-speed USB signal pairs and other signal traces for optimal signal quality.
   與其他信號間隔 最少20mil
5. The minimum suggested spacing to clock signals is 50 mils.
   距離時鐘信號，最少50mil

HDMI

1. TMDS pairs (HDMI TX and HDMI RX) must be routed on top layer without any vertical interconnect access (vias).
   TMDS信號線走單層，避免使用過孔
2. To minimize impedance discontinuities, cut out ground plane on layer 2 underneath the TMDS pads of the HDMI connector,                                                                                                                                                                                  走線的參考層進行特殊處理                                                                                                                                          
3. A minimum inter-pair spacing of 30 mils is recommended. The spacing between a TMDS pair and a clockor periodic signal should be at least 50 mils.                                                                                                                                                         差分對間間距30mil   與其他信號間距50mil