Overview
1
Keysight E6960A User Guide and Method of Implementation
35
MDI Return Loss Test Information
Reference [2] specifies that the differential impedance at the MDI for each
transmit/receive channel shall be such that any reflection (due to differential
signals incident upon the MDI with a test port having a differential impedance of
100
Ω
) is attenuated relative to the incident signal as per the equation below.
where f is the frequency in MHz.
In other words, the return loss shall meet or exceed the equation above for all
frequencies ranging from 2 MHz to 600 MHz (with 100
Ω
differential impedance) at
all times when the PHY is transmitting data or control symbols.
ReturnLoss f
( )
18 18
10
log
(
)
20
f
------
–
2 f 20
<
≤
18
20 f 100
<
≤
18 16.7
10
log
(
)
f
100
---------
–
100 f 600
≤ ≤
≥
