If a PCB is to encompass Ethernet, USB, and 1394 (FireWire), are 3 separate differential impedance pairs required? Here are the requirements from the respective specs: Ethernet: 90 ohm +/- 15%; USB: 110 +/- 10%; 1394: 110 +/-10%. A PC motherboard designer should be able to answer this. Thanks in advance, [log in to unmask]