Teledyne LeCroy Eye Doctor II - Manual (Page 13)

Operator's Manual
Examples of Auto Add Pre-emphasis (center) and De-emphasis (right)
along with no emphasis (left).
The analysis for each lane shows three plots Eye diagrams(top grids), and two waveforms. The wave-
forms are as follows:
l
The blue waveform is a zoom of the SDAInput trace, which is the output of the Signal step in the
SDA processing chain. (In this case, it is a copy of F1, but if we were using two inputs, such as C1
and C2 to receive a differential signal, SDAInput would be C2-C1.)
l
The orange waveform is a zoom of the Emp trace, which shows the output of the Emphasis block.
Lane1 (left) is configured with emphasis turned off, and is shown for reference. (The Emp trace is equal to
SDAInput).
Lane2 (center) is configured to add pre-emphasis. The Emp trace shows a gain in the amplitude for tran-
sitional bits (the first bit after a rising or falling edge). The eye diagram shows multiple levels as a result of
the added pre-emphasis, with the emphasized bits causing an increase in the overall peak-peak voltage.
Lane3 (right) is configured to add de-emphasis. The Emp trace shows a attenuation for all non-tran-
sitional bits (bits that are not the first bit after a rising or falling edge). The eye diagram shows multiple lev-
els as a result of the added de-emphasis, with the emphasis appearing within the un-emphasized eye
such that the overall peak-peak voltage is not increased.
922961 Rev A 11