Ethernet PHY

Ethernet PHY (or physical layer)

"How to design 100BASE-TX Ethernet schematics" (opens in a new tab)

  • 0402 or 0201 capacitors for decoupling input voltage
    • Placed very close to IC
    • Use correct capacitances
  • MDI pins (twisted pairs over the PHY) are differential pairs and have 100 ohm impedance matching
  • Resistors should be 1% tolerance
  • Ethernet reference clocks are important
  • Magnetics should include common mode chokes and magnetics
    • Common mode chokes should face cable side (closer to connector?)
    • Center tab connected to ground through decoupling capacitors
    • Bob smith termination to reduce noise?
    • System GND and Earth GND should have 1M resistor and 4700pF cap across in parallel