Teledyne LeCroy Eye Doctor II - Manual (Page 14)

Eye Doctor II Software
Auto Remove Emphasis
Auto Remove Emphasis automatically determines the appropriate tap values for your input signal when
the amount of emphasis to remove is specified in the Gain box.
Either pre-emphasis or de-emphasis can be automatically removed. Use this feature when seeking to
make jitter and noise measurements on emphasized signals that have not been "naturally" de-empha-
sized by passing through a channel.
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Remove Pre-emphasis - This implements an 8-tap FFE filter that attenuates the amplitude of tran-
sitional bits in your input signal input signal by the Gain amount specified.
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Remove De-emphasis - - This implements an 8-tap FFE filter that boosts the amplitude of tran-
sitional bits in your input signal by the Gain amount specified.
The image below uses SDAIII-CompleteLinQ ability to perform multi-lane analysis simultaneously to illus-
trate the effect of removing pre-emphasis and de-emphasis. It shows three lanes being analyzed, with
each lane containing a simulated 5Gbps NRZ pattern configured on F1 using the JitSim function.
Auto-remove of 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:
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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.)
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The orange waveform is a zoom of the Emp trace, which shows the output of the Emphasis block.
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