AMI Bathtub Charts

The AMI bathtub report can illustrate curves of the Bit Error Rate (BER) at four points in the circuit:

The Initial Waveform shows the Piecewise Linear data input to the transmitter, including any jitter.
The Waveform After Source shows the output on the transmitter.
The Waveform After Channel shows the input to the receiver.
The Waveform After Probe shows the output on the receiver.

Note: With AMI plots, when Bathtub curves can be plotted and txrj is present, a warning message is displayed if the number of bits is less than 2.5e5.

To plot the bathtub diagram:

Select Create Standard Report>Rectangular Plot.
Select the following:
- Solution: AMI Analysis
- Domain: UI
- Quantity: InitialEye, EyeAfterSource, EyeAfterChannel, or EyeAfterProbe
- Primary Sweep: _UnitInterval
- Function: <none>

The following chart shows the BER bathtub curve for the Initial Eye waveform. From the Y-Axis, the Scaling is set to Log, with Max 0.6 and Min 1e-15.

AMI BER Bathtub Curve

With modulation=PAM4, plot the symbol error rate. PAM4 symbols are two bits. Click the same Report setup, but select the <Symbol Error Rate> trace.

AMI Bathtub SER Trace

For bathtub curves of AMI, distinguish simulated and extrapolated regions with a partitioning horizontal line using the ‘SimulatedLimit’ option that is in the ‘Quantity’ column. For more information, please see Display Quick Eye Analysis Outputs.