Configuration

Configure system wide settings in SerDes system model

• Library:

• SerDes Toolbox / Utilities

• 

Description

The Configuration block sets the system-wide settings of a SerDes system, such as symbol time, samples per symbol, target bit error rate (BER), modulation scheme, and signaling type. It also configures the generation of IBIS and AMI models and customizes the AMI parameters.

Limitations

• Non-inlined S-functions are not supported for IBIS-AMI model export. If you have a Simulink^® Coder™ or Embedded Coder^® license, you can convert your S-functions to inlined to support IBIS-AMI model export.

Parameters

Symbol time (s) — Time of single symbol duration

100e-12 (default) | real positive scalar

Time of a single symbol duration, specified as a real positive scalar in s.

Programmatic Use

• Use get_param(gcb,'SymbolTime') to view the current value of Symbol time (s).

• Use set_param(gcb,'SymbolTime',value) to set Symbol time (s) to a specific value.

Data Types: double

Samples per symbol — Data points per symbol

16 (default) | 8 | 32 | 64 | 128

Number of data points per symbol.

Programmatic Use

• Use get_param(gcb,'SamplesPerSymbol') to view the current value of Samples per symbol.

• Use set_param(gcb,'SamplesPerSymbol',value) to set Samples per symbol to a specific value.

Data Types: double

Sample interval (s) — Uniform time step of waveform

6.25e-12 (default) | real positive scalar

Uniform time step of the waveform, specified as a real positive scalar in s. This parameter is read-only and is derived from Symbol time (s) and Samples per symbol.

Programmatic Use

• Use get_param(gcb,'SampleIntervalText') to view the current value of Sample interval (s).

Data Types: double

Target BER — Target bit error rate

1e-6 (default) | real positive scalar

Target bit error rate used to generate eye-contours, specified as a unitless real positive scalar.

Programmatic Use

• Use get_param(gcb,'TargetBER') to view the current value of Target BER.

• Use set_param(gcb,'TargetBER',value) to set Target BER to a specific value.

Data Types: double

Modulation — Modulation scheme

'NRZ' (default) | 'PAM4'

Number of logic levels in the modulation scheme:

• Select 'NRZ' if the modulation scheme has two logic levels.

• Select 'PAM4' if the modulation scheme has four logic levels.

Programmatic Use

• Use get_param(gcb,'Modulation') to view the current value of Modulation.

• Use set_param(gcb,'Modulation',value) to set Modulation to a specific value.

Data Types: char

Signaling — How signal is transmitted through wires

'Differential' (default) | 'Single-ended'

How the incoming signal is transmitted through wires:

• 'Differential' — Transmit the incoming signal using a differential pair of signals. The receiver responds to the difference between the two signals.

• 'Single-ended' — Transmit the incoming signal using a varying voltage. The receiver responds to the difference between the incoming signal and a reference or ground.

Signaling only affects the generated IBIS files. Voltage levels in Simulink do not change when changing the signaling type. Signaling also affects the Impedance of Analog Channel when the Channel model is Loss model.

Programmatic Use

• Use get_param(gcb,'Signaling') to view the current value of Signaling.

• Use set_param(gcb,'Signaling',value) to set Signaling to a specific value.

Data Types: char

Plot statistical analysis after simulation — Plot statistical analysis after simulation

on (default) | off

Select to plot the statistical analysis (Init) results after the simulation is run. By default, this option is selected. The results derived from the equalized impulse response includes the pulse response, waveform, statistical eye, and statistical eye metrics (eye height, eye width, eye area, channel operating margin, and vertical eye closure).

Plot time domain analysis after simulation — Plot time analysis after simulation

on (default) | off

Select to plot the time domain analysis results after the simulation is run. By default, this option is selected. The result includes time domain eye with clock ticks histogram and time domain eye metrics (eye height, eye width, eye area, channel operating margin, vertical eye closure, and minimum BER).

The time domain eye is derived from the output of the receiver blocks and the clock ticks generated by the DFECDR, CDR block, or IBIS-AMI clock_times block. To generate a meaningful time domain eye, the maximum value of the Bits to ignore parameter for Tx and Rx in the Export tab of the SerDes IBIS-AMI Manager dialog box is used.

Open SerDes IBIS-AMI Manager — Open SerDes IBIS-AMI Manager

button

Click to open the SerDes IBIS-AMI Manager dialog box. Using this dialog box, you can set the IBIS and AMI file contents and export the IBIS-AMI model.

Set the model configuration (Tx and Rx, I/O, redriver, retimer), IBIS settings (model names, corner percentage), and AMI model settings (model type, bits to ignore) for the transmitter and receiver and specify file creation options in the Export tab of the SerDes IBIS-AMI Manager dialog box.

The IBIS tab of the SerDes IBIS-AMI Manager dialog box contains the IBS file contents.

You can add customized AMI parameters, additional tap structure, and jitter and noise profiles using the AMI-Tx and AMI-Rx tabs. For more information, see Manage IBIS-AMI Parameters.

More About

Eye Metrics

You can view the performance metrics of statistical and time domain eye by plotting the statistical and time domain results.

Performance Metric	Description
Eye Height (V)	Eye height at the center of the BER contour
Eye Width (ps)	Eye width of the BER contour
Eye Area (V*ps)	Area inside the BER contour eye
Eye Linearity	Measure of the variance of amplitude separation among different levels of PAM3 or PAM4, given by the equation: $$\text{Linearity}=\frac{\text{Minimum amplitude of the different eye levels}}{\text{Maximum amplitude of the different eye levels}}$$
COM	Channel operating margin, given by the equation: $$\text{COM}=20{\log }_{10}\left(\frac{\text{Mean eye height}}{\text{Mean eye height - Inner eye height}}\right)$$
VEC	Vertical eye closure, given by the equation: $$\text{VEC}=\frac{\text{Mean eye height}}{\text{Inner eye height}}$$
Minimum BER	Minimum BER possible based on number of symbols and ignored bits set in the SerDes IBIS-AMI Manager dialog box, given by the equation :$$\text{Minimum BER=}\frac{1}{\left(\text{Number of symbols}-\text{Ignored bits}\right)}$$ Minimum BER should be greater than or equal to target BER.

Note

Mean eye height is defined as the height of the eye between the densest part of eye histogram below and above the inner eye.

Generating Meaningful Time Domain Eye

The time domain eye represents the results of the time domain analysis derived from the output of the receiver and, if generated, the clock ticks. To generate a meaningful time domain eye, it is important to ignore the results from a preliminary number of bits from the transmitter and receiver while the equalization algorithms are adapting to find the optimum configuration. You can set the number of bits to ignore by setting the Tx and Rx Bits to Ignore parameter in the Export tab of the SerDes IBIS-AMI Manager dialog box. For time domain analysis, the maximum value of the two Bits to Ignore parameters is ignored. Depending on how many bits are ignored, the eye and associated metrics of the time domain eye might change.