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Manage Contents of IBIS and AMI files

You can manage the IBIS-AMI parameters by opening the SerDes IBIS-AMI Manager dialog box from the Configuration block.

Contents of IBIS File

The IBIS tab in the SerDes IBIS-AMI Manager dialog box defines the content of the IBIS file. Set the parameters used to define the IBIS file in the AnalogOut and AnalogIn blocks in the SerDes Designer app and in the IBIS tab in the SerDes IBIS-AMI Manager.

From the transmitter side in the AnalogOut block:

  • Voltage (V) — Typical value of voltage range in the IBS file.

  • R (Ohms) — Slope of the typical pull-up and pull-down IV curves in the IBS file.

  • C (pF) — Typical value of the C_comp in the IBS file.

From the receiver side in the AnalogIn block:

  • Voltage (V) — Typical value of voltage range in the IBS file.

  • R (Ohms) — Slope of the typical ground clamp IV curve in the IBS file.

  • C (pF) — Typical value of the C_comp in the IBS file.

You can only enter the typical values for these parameters. You can define the Tx and Rx corner percentage in the Export tab of the SerDes IBIS-AMI Manager dialog box. The minimum and maximum values are generated by subtracting or adding to the typical value its fractional corner percentage.

The performance of an input/output (I/O) buffer is a function of process, voltage, and temperature (PVT). There are 27 PVT corners. IBIS supports three model corners: Typ, Min, and Max. When generating the IBIS file, the Voltage (V), R (Ohms), and C (pF) values are used for the Typ corner.

  • Min refers to the slow/weak corner. It groups slow process, low voltage, and high temperature. The voltage and resistance are decreased and the capacitance is increased for the Min corner.

  • Max refers to the fast/strong corner. It groups fast process, high voltage, and low temperature. The voltage and resistance are increased and the capacitance is decreased for the Max corner.

You can also specify the IBIS-AMI model in the Export tab of the SerDes IBIS-AMI Manager dialog box as single I/O, redriver, or retimer. Selecting these model configurations changes the contents of the IBIS file.

  • If you select I/O as the model configuration, the IBIS model is reconfigured to a single model of Model Type I/O.

  • If you select Retimer or Redriver as the model configuration, the components of the IBIS file is updated to include the repeater pins.

Contents of AMI File

The AMI - Tx and AMI - Rx tabs in the SerDes IBIS-AMI Manager dialog box define the content of the AMI file. They contain the required and commonly used reserved AMI parameters. You can also define the model-specific parameters for the relevant blocks.

There are five Reserved_Parameters included in every AMI file generated by the SerDes Toolbox™:

  • AMI_Version — IBIS version supported by the model

  • Init_Returns_Impulse — whether the model supports statistical simulation or not

  • GetWave_Exists — whether the model supports time-domain simulation or not.

  • Max_Init_Aggressors — the number of crosstalk aggressors supported by the model

  • Modulation — the modulation scheme of the model.

  • Ignore_Bits — the number of bits ignored during time domain analysis.

If you select Retimer or Redriver as the model configuration in the Export tab of the SerDes IBIS-AMI Manager dialog box, an additional Reserved_Parameter Repeater_Type is added to the AMI - Rx tab. This parameter specifies the type of the repeater.

Customize AMI Parameters

You can define and modify the parameters of individual transmitter and receiver blocks. From the Model_Specific parameters, you can add new custom AMI parameters to specific blocks. The new AMI parameters references in the Simulink® model are automatically maintained for you. For more information, see Managing AMI Parameters.

You can also add a new tap structure to the equalizer blocks. These additional taps are included both in the Simulink model and the exported IBIS-AMI models. The taps enable you to adjust equalization, especially when you build your custom blocks from scratch.

You can select to hide the Model_Specific AMI parameters and tap structures using the Edit... button The parameters still work the same way in Simulink models. But they are not written in the AMI files and does not show up in the AMI_Parameters_Out string. The hidden parameters are hard-coded to their current values in the DLL files and the end user cannot modify them.

You can also include standard-compliant transmitter and receiver jitter and noise parameters to the Reserved_Parameter section of the AMI file using the Reserved Parameters... button. Some of these reserved parameters are only used by the EDA tools. Simulink Coder™ ignores these parameters:

  • Rx_Decision_Time

  • Ts4file (and Tx_V, Rx_R)

  • Rx_Clock_Recovery_Mean

  • Rx_Clock_Recovery_Rj

  • Rx_Clock_Recovery_Dj

  • Rx_Clock_Recovery_Sj

  • Rx_Clock_Recovery_DCD

Define Clock Position in Statistical Eye

You can define the timing of the clock in the statistical eye according to BIRD 205 using the reserved parameter Rx_Decision_Time. The corresponding Init function code, data structure, and AMI tree is automatically supported.

To add the Rx_Decision_Time parameter, click the Reserved Parameters... button in the AMI-Rx tab to open the Add/Remove dialog box. Once you add the parameter, it appears in the AMI tree. A model workspace variable is also created You need to refresh the Init function in the receiver after you modify the Rx_Decision_Time parameter. After refreshing the Init function, the parameter appears in the Custom User Area.

Note

The Rx_Decision_Time parameter is only added in the receiver section.

PAMn Capabilities

The SerDes IBIS-AMI manager supports NRZ, PAM3, PAM4, PAM8, and PAM16 modulation schemes. If your model previously was created using IBIS pre-7.2 modulation levels, you can switch to IBIS 7.2 parameter Modulation_Levels by editing the Modulation AMI parameter under the Reserved_Parameter section. Switching to IBIS 7.2 parameter Modulation_Levels requires refreshing the Init function in the receiver side. The changes are applied both to transmitter and the receiver side.

Debug AMI Files in EDA

To enable debugging the AMI files in EDA tools, in the AMI-Tx or AMI-Rx tab, click the Reserved Parameters... button and select DLL_ID parameter. DLL_ID is a standard IBIS-AMI parameter that appears as a Reserved_Parameter. It also enables the AMI_Debug parameter as a Model_Specific parameter.

Set Enable value to true to output debug files. You can improve performance by setting Enable value to false and not output any debug files, but still have the option to turn on debugging in the EDA tools if necessary. Use Start_Time to define the simulation time at which debug output generation begins.

Note

SerDes Toolbox does not support compilation of AMI_Wrapper.cpp files with non-inlined S-functions. As a result, you cannot export IBIS-AMI models with non-inlined S-functions. If you have a Simulink Coder or Embedded Coder® license, you can convert your S-functions to inlined to support IBIS-AMI model export. For more information, see Inlining S-Functions (Simulink Coder).

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