Microsemi AC483 PolarFire FPGA Transceiver Signal Integrity User Guide

AC483 Polarize FPGA Transceiver Signal Integrity
User Guide

AC483
Application Note
Polar Fire FPGA Transceiver Signal Integrity

AC483 Polar Fire FPGA Transceiver Signal Integrity

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Revision History

The revision history describes the changes that were implemented in the document. The changes are listed by revision, starting with the current publication.
1.1 Revision 2.0
• Added Enhanced Receiver Management options in Libero Flow, page 16.
• Added new Rx CTLE settings, see Table 5, page 13.
1.2 Revision 1.0
The first publication of this document.

Transceiver Tuning

This document describes the several Polar Fire Transceiver signal integrity settings as well as IBIS-AMI and Smart Debug features.
The document covers the design flow required to perform successful signal integrity tuning at both
Transmitter (Tx) and Receiver (Rx) end. For commonly used terminologies, see Glossary, page 23.
Transceiver tuning for Polar Fire devices is done three different ways:

• Traditional Method (Non-simulation flow): Traditional method is based on learnings developed from experience. If costumers know the channel loss, then based on the  recommendations provided in this document or on the basis of users experiences, Transceiver attributes are loaded to the device. This method does not guarantee the ideal Transceiver performance.

• IBIS-AMI Simulations: Transceiver tuning based on IBIS-AMI Simulations is the best method available. Simulations helps to build confidence on the performance of the  hardware. In simulations, both the transmitter and receiver variables can be changed and output is observed. This method provides a clear image on how the  different Transceiver attributes impacts the performance of the system. The appropriate Transceiver attributes obtained from the simulation can be applied to the device by two ways:

• Through Libero: Change the attributes in the design while generating the bit file.

• Through Smart Debug: The Smart Debug tool provides the facility to vary between the multiple attributes using the same bit file.
  Detailed explanation of tuning using IBIS-AMI Simulations is provided in this document.

• Smart Debug: Smart Debug is used for debugging the Transceiver using electrical parameters such as Tx amplitude, De-emphasis, driver impedance, Rx impedance,  CTLE and DFE calibration. It gives freedom to the users to play with the signal integrity settings based on the simulations or intuitions. Details of Smart Debug are  discussed in the later section of this document. For more information, see Smart Debug User Guide for Polar Fire FPGAs.
  Note: Receiver optimization is disabled in Libero SoC v12.0 Smart Debug. It will be fixed in a future version.
  Polar Fire transceivers have a memory mapped Dynamic Reconfiguration Interface (DRI) which allows Smart Debug to communicate with the transceiver blocks in real- time. This feature provides debugging capabilities and altering of the transceivers for optimized performance in the system. After the final Smart Debug signal integrity  optimization, the user can export the tuned information back into the Libero SoC software for future design regeneration.

Figure 1 • Transceiver Signal Integrity Tuning Flow

2.1 Transmitter
High speed transmitter has following capabilities that user can adjust to make the system work. Note that only transmitter tuning alone does not help for high loss channel,  receiver tuning is also required to make system work without errors.

• Amplitude: Transmitter supports 10 amplitude settings from 100mV to 1000mV in steps of 100mV.
• De-emphasis: Transmitter supports six de-emphasis settings. Those are 0dB, -1dB, -2.5dB, -3.5dB,-4.4dB and -6dBmV.
• Termination impedance: Transmitter supports four driver terminations. Those are 85 Ω, 100 Ω,150 Ω and 180 Ω.
• Jitter: In the IBIS-AMI simulation, the following Jitter parameters can be used for the transmitter:
• TX (Tx Duty cycle Distortion)
• TX (Tx Deterministic Jitter)
• TX (Tx Random Jitter)
  Note: See Polar Fire IBIS-AMI Models for the worst-case jitter numbers. By default, these jitter numbers are considered while running IBIS-AMI simulations.
  The following table describes the recommended Tx settings for different channel lengths.

Table 1 • Recommended Driver Amplitude, De-emphasis, Impedance Settings

Amplitude and De-emphasis Setting (mV with dB)| Tx Termination (Ω)| Recommended channel
---|---|---
100mV with 0dB| 100| Very Short
200mV with 0dB| 100| Very Short
200mV with -1dB| 100| Very Short
200mV with -2.5dB| 100| Very Short
200mV with -3.5dB| 100| Very Short
200mV with -4.4dB| 100| Very Short
200mV with -6dB| 100| Very Short
300mV with 0dB| 100| Short
400mV with 0dB| 100| Short
400mV with -1dB| 100| Short
400mV with -2.5dB| 100| Short
400mV with -3.5dB| 100| Short
400mV with -4.4dB| 100| Short
400mV with -6dB| 100| Short
500mV with 0dB| 100| Short
600mV with -3.5dB| 150| Short/Medium
600mV with -6dB| 150| Short/Medium
800mV with 0dB| 150| Short/Medium/Long
800mV with -1dB| 150| Short/Medium/Long
800mV with -2.5dB| 150| Short/Medium/Long
800mV with -3.5dB| 150| Short/Medium/Long
800mV with -4.4dB| 150| Short/Medium/Long
800mV with -6dB| 150| Short/Medium/Long
1000mV with 0dB| 180| Short/Medium/Long
1000mV with -1dB| 180| Short/Medium/Long
Amplitude and De-emphasis Setting (mV with dB)| Tx Termination (Ω)| Recommended channel
---|---|---
1000mV with -2.5dB| 180| Short/Medium/Long
1000mV with -3.5dB| 180| Short/Medium/Long
1000mV with -4.4dB| 180| Short/Medium/Long
1000mV with -6dB| 180| Short/Medium/Long

Note: Apart from these recommended settings, each driver termination (85,100,150 and 180 Ω) has 29 amplitude and emphasis settings ranging from 100mV with 0dB to  1000mV with -6dB. User can apply any of the recommended or other settings to the silicon according to their applications.

2.1.1 IBIS-AMI
The Tx parameters are accessed in the IBIS-AMI simulation in the following ways:

• Amplitude and De-emphasis is through the variable Amphorae.
• Driver Termination is the through selecting the appropriate pin in the IBIS as listed in the following table.
  Table 2 • Tx Model Pin Description

The PolarFire IBIS-AMI models can be downloaded from link https://www.microsemi.com/products/fpgasoc/design-resources/ibis-models/ibis- models-polarfire.
The following table shows the IBIS-AMI model files contained in the model package files and its  descriptions.

Table 3 • IBIS-AMI Model File Description

model.
MPF300T-TX-R085.ami| All Amplitude and de-emphasis settings with 85 0 termination, full set of settings are present in this transmitter AMI model.
MPF300T-TX-R100.ami| All Amplitude and de-emphasis settings with 100 0 termination, full set of settings are present in this transmitter AMI model.
MPF300T-TX-R150.ami| 1000mv amplitude settings with 150 0 termination
MPF300T-TX-R150_800.ami| 800mv and 600mv amplitude settings with 150 0 termination
MPF300T-TX-R150_400.ami| 100mv to 500mv amplitude settings with 150 0 termination
MPF300T-TX-R180.ami| 1000mv amplitude settings with 180 0 termination
MPF300T-TX-R180_800.ami| 800mv and 600mv amplitude settings with 180 0 termination
MPF300T-TX-R180_400.ami| 100mv to 500mv amplitude settings with 180 0 termination

2.1.2 Libero Flow
The Tx and Rx settings obtained from IBIS-AMI simulation can be directly applied to the device through Libero. In this section, settings related to Tx are discussed.  Following are the steps to apply Tx signal integrity settings.
To create the transceiver based design:

1. Run the Synthesize, this enables the Manage Constraints
2. Go to Manage Constraints
3. Go to I/O Attributes
4. Select the Target
5. Click Edit > Edit with I/O Editor as show in the following figure

After the I/O Editor is opened, perform the following steps:

1. Select XCVR View tab.
2. Select the appropriate lane.
3. Go to Signal Integrity View present in the right bottom as shown in the following figure.
4.  Set the Tx settings such as, Amplitude with de-emphasis, Tx Impedance as shown in the following figure.

XCVR view tab provides options to apply different Tx settings and Termination impedance. Select the appropriate settings and apply. After this step, both Tx and Rx settings  are applied to Transceiver.
This fixes the Tx and Rx settings into staple (bit file) file. In-order to debug the design with respect to signal integrity, change the Tx and Rx settings through Smart Debug on the fly.

2.1.3 Smart Debug Flow
When the design is not working as expected, Smart Debug is used to debug the design with respect to signal integrity related issues. For more information on Smart Debug,  see Smart Debug User Guide for Polar Fire FPGAs.
For Tx, Smart Debug is used to change the settings such as amplitude, de- emphasis and driver termination settings live on the hardware. There are two ways the hardware can be debugged.

1. Use existing design which sends data.
2. Use in-built PRBS generator from Smart Debug.
   Note: Only Tx settings are discussed in this section, however, for successful debug, both Tx and Rx need to be tuned. For Rx setting, see Receiver, page 11

Following steps describe the debugging of the design with respect to Tx.

1. Program the bit file (.step) on to the device.

2. Open the corresponding Libero Project.

3. Double click the Generate Smart Debug FPGA Array Data on Libero Software. Once the array data is generated, a green tick mark appears as shown in the following figure.
   Figure 4 • Smart Debug FPGA Array Data

4. After generating the data successfully open the Smart Debug Design from the Libero Design Flow.
   Note that the Hardware has to be connected with Flash Pro programmer and power on. If the Smart Debug is opened without powering up the hardware, it opens up in  Demo Mode. Connect the hardware using Flash Pro programmer and open the Smart Debug Design from the Libero Design Flow. It opens Smart Debug window as  shown in the following figure. Click Debug Transceiver.

5. Go to Smart BERT tab and select the required lane to assign the pattern and Transmitter attributes as shown in the following figure. Select any data pattern or the  existing design sends the data pattern.

6. From the drop down menu select the Tx Emphasis amplitude. Selected option sets the device registers to provide the desired de-emphasis for the particular signal  amplitude. Tx impedance is also decided based on the signal amplitude.

7. After all the step are completed, click Apply for new settings on the device.

8. The inbuilt PRBS generator can be used to send out the data pattern. To enable PRBS generator select appropriate PRBS pattern and click Start on the Smart Bert  window as shown in the following figure.

2.1.4 Illustration
This section describes an example for testing the performance of IBIS-AMI model using Polar Fire Evaluation Kit.
Device and Setup Details

• Device Used: MPF300T-1FCG1152.
• Transceiver block: Two Lane 0 is used for measurement.
• Dedicated internal reference clock is used for the SERDES block (156.25MHz).
• LVDS25 IO standard is used to reference clock input.
• 23GHz Tektronix (DPO72304) scope and 100G samples/sec setting is used for measuring jitter and plotting eye.
• Two feet long cable (part# Scolex 100 126E) is used for connecting the Tx ports to the scope.
• 2.3 inch long trace is connecting the device and the Tx SMA ports.
• Clock Recovery Configuration:- Method: PLL-Custom BW, PLL Model: Type II, Damping:700m In the measurement the appropriate Tx settings is loaded to the silicon through Smart Debug as explained in Smart Debug Flow, page 7.Use the inbuilt PRBS31 generator to send the data out. Following figure shows the hardware setup used for the measurement.Design used to test the transmitter performance of the IBIS-AMI model is shown in the following figure. With the help of sweep option different de-emphasis settings is  tested and the one which provides the best result is then loaded to Smart Debug. Measurement result is obtained with the best suited settings which is correlated with the simulation to fine tune the model.

The IBIS-AMI Tx model is connected to pass through Rx model which is a simple 100 Ω termination through die parasitic, package, board and 24 inch cable s-parameter  model. The measurement environment is created virtually through the design in ADS.
Parameter sweep option is used to test the 29 different de-emphasis setting marked as 1 to 29 with each corresponding to a specific value of signal amplitude and de-emphasis.
Figure 10, page 11 shows the correlation between measurement and IBIS-AMI simulation for following settings:

• Tx Amplitude: 800 mV
• De-emphasis: 0 dB
• Tx Termination: 150 Ω
• Data Rate: 10.3125 Gbps
  Simulated Tx Eye correlates well with measurement as shown in following figure.

Note: Blue represents Simulation and Red represents Measurement.
2.2 Receiver
High speed data coming from transmitter passing through a channel can result in degradation of the signals and making it difficult for the receiver to detect it correctly. As the  data rate increases, equalization at the receiver becomes a necessity. Equalizers are used to compensate the high frequency losses included by the channel. Analog  equalization is done by Continuous Time Linear Equalizers (CTLE) whereas discrete time equalization can be achieved by Decision Feedback Equalization (DFE). For lower  data rates CTLE is sufficient, however, for higher data rate DFE is also used along with CTLE. Polar Fire Rx supports 85 Ω, 100 Ω and 150 Ω terminations. The Receiver provides three types of equalizations as explained:

• CDR Mode: This option provides users to apply any CTLE setting including the recommended (Default values in the Libero) ones or settings obtained from the IBIS-AMI simulations.
• CDR Mode with Calibration : The device internal algorithm optimizes the receiver and applies the best CTLE settings in the device for the given channel and Tx attributes.
• DFE Mode: Polar Fire transceiver is built with a five tap DFE engine. DFE is used when the data rate is high or loss of the channel is too high. DFE is always used along  with CTLE. In CDR Mode with calibration, the device optimizes the receiver and provides best CTLE and associated DFE coefficients. DFE in IBIS-AMI simulations is only used to sign-off the hardware.

For receiver tuning 63 CTLE settings are provided. Libero default CTLE settings are assigned for a particular data rate range and channel however other settings can also be  used for the same range as shown in the following table.

Table 4 • Default Rx CTLE Settings

The following table contains the information about all 63 CTLE settings and the recommended data rate range in which they are used. Note that user can set any settings for any data rate.
Table 5 • Rx CTLE Settings

S.No.| RX_CTLE Settings| DC Gain (dB)| Peak AC Gain (dB)| Data Rate (Mbps)
---|---|---|---|---
1| NoPeak+7.3dB| 7.27| 7.28| 250 – 1600
2| NoPeak+9.3dB| 9.28| 9.29| 250 – 1600
3| NoPeak+2.8dB| 2.85| 3.07| 250 – 1600
4| 3Ghz+5.5dB| -2.28| 3.17| 250 – 1600
5| 3Ghz+11.4dB| -7.98| 3.46| 250 – 1600
6| NoPeak+2.82dB| 2.82| 2.84| 250 – 1600
7| NoPeak+0.1dB| 0.12| 0.13| 250 – 1600
8| NoPeak-2.5dB| -2.57| -2.48| 250 – 1600
9| NoPeak-7.1dB| -7.15| -6.86| 250 – 1600
10| 3GHz+4.62dB| -13.00| -8.38| 250 – 1600
11| NoPeak+4.6dB| 4.61| 4.62| 250 – 1600
12| NoPeak+1.8dB| 1.86| 1.88| 250 – 1600
13| NoPeak-0.9dB| -0.94| -0.87| 250 – 1600
14| NoPeak-5.6dB| -5.61| -5.42| 250 – 1600
15| 3GHz+4.6_dB| -11.60| -6.99| 250 – 1600
16| 3GHz+11.0dB| -9.34| 1.71| >1600 – 5000
17| 3GHz+5.6dB| -6.43| -0.77| >1600 – 5000
18| NoPeak-1.1dB| -1.17| -0.62| >1600 – 5000
19| 3GHz+12.3dB| -12.77| -0.44| >1600 – 5000
20| 3GHz+2.3_dB| -6.48| -4.18| >1600 – 5000
21| 3GHz+9.0dB| -12.96| -3.90| >1600 – 5000
22| 3GHz+5.9dB| -5.02| 0.90| >1600 – 5000
23| NoPeak+0.3dB| 0.37| 1.01| >1600 – 5000
24| 3GHz+12.6dB| -11.37| 1.24| >1600 – 5000
25| 3GHz+2.4dB| -5.07| -2.66| >1600 – 5000
26| 3GHz+9.1dB| -11.54| -2.37| >1600 – 5000
27| 3GHz+1.4dB| 4.55| 5.96| >5000 – 6875
28| 3GHz+6.8dB| -2.32| 4.53| >5000 – 6875
29| 3GHz+12.9dB| -8.07| 4.88| >5000 – 6875
30| 3GHz+7.8dB| -5.11| 2.70| >5000 – 6875
31| 3GHz+2.2dB| 0.29| 2.57| >5000 – 6875
32| 3GHz+14.5dB| -11.50| 3.05| >5000 – 6875
33| 3GHz+4.8dB| -5.16| -0.29| >5000 – 6875
34| 3GHz+11.8dB| -11.67| 0.17| >5000 – 6875
35| 5GHz+1.8dB| 4.56| 6.36| >6875 – 8437.5
36| 5GHz+7.3dB| -2.30| 5.03| >6875 – 8437.5
S.No.| RX_CTLE Settings| DC Gain (dB)| Peak AC Gain (dB)| Data Rate (Mbps)
---|---|---|---|---
37| 5GHz+13.4dB| -8.07| 5.38| >6875 – 8437.5
38| 5GHz+8.4dB| -5.11| 3.33| >6875 – 8437.5
39| 5GHz+2.8dB| 0.30| 3.14| >6875 – 8437.5
40| 5GHz+15.1dB| -11.50| 3.68| >6875 – 8437.5
41| 5GHz+5.7dB| -5.16| 0.58| >6875 – 8437.5
42| 5GHz+12.7dB| -11.70| 1.09| >6875 – 8437.5
43| 5GHz+9.8dB| -5.43| 4.40| >8437.5 – 10312.5
44| 5GHz+12.4dB| -8.09| 4.35| >8437.5 – 10312.5
45| 5GHz+9.6dB| -5.40| 4.22| >8437.5 – 10312.5
46| 5GHz+10.6dB| -5.38| 5.20| >8437.5 – 10312.5
47| 6GHz+11.1dB| -4.34| 6.79| >10312.5
48| 6GHz+10.1dB| -4.34| 5.79| >10312.5
49| 6GHz+10.13dB| -4.18| 5.95| >10312.5
50| 6GHz+12.2dB| -10.14| 2.06| >10312.5
51| 6GHz+11.0dB| -6.82| 4.24| >10312.5
52| 6_GHz+12.0dB| -6.97| 5.07| >10312.5
53| 6GHz+11.5dB| -7.25| 4.28| >10312.5
54| 6GHz+13.1dB| -7.17| 5.92| >10312.5
55| NoPeak+9.22 dB| 9.22| 9.24| >8437.5 – 10312.5
56| NoPeak+4.53 dB| 4.53| 4.55| >8437.5 – 10312.5
57| NoPeak+1.76 dB| 1.76| 1.78| >8437.5 – 10312.5
58| 5GHz+3.14 dB| -1.52| 1.61| >8437.5 – 10312.5
59| NoPeak+11.10 dB| 11.10| 11.13| >10312.5
60| NoPeak+6.13 dB| 6.13| 6.15| >10312.5
61| NoPeak+3.39 dB| 3.39| 3.41| >10312.5
62| 6GHz+2.73 dB| 0.32| 3.06| >10312.5
63| 6GHz+3.12 dB| 1.50| 4.62| >10312.5

For higher dates rate, 5 tap DFE is used along with CTLE. Libero sets the default DFE and CTLE settings for given channel and data rate as shown in following table.
Note: These settings are used when auto calibration of DFE is not selected.

Table 6 • Default Rx DFE Coefficients

2.2.1 IBIS-AMI
This section describes the IBIS-AMI Rx model parameters that needs to be varied in order to obtain proper tuning of the receiver. In Rx model, AMI tab contains four  important parameters used for receiver optimization. The following table lists the information about the four key parameters.

Table 7 • Rx Model Parameter Descriptions

provided. Detailed description of the complete 63 settings are provided in Tab le 5,  page 13.
DFE_MODE| Determine the DFE calibration mode.
1=off, 2=fixed, 3=adapt.
Adapt mode does auto calibration of the device to obtain the best DFE coefficients where as in fixed mode coefficients are added manually.
DFE_TAP| 5 Tap DFE is used.
Each tap can be manually edited by the costumers in DFE_MODE=2 or DFE_MODE=3.
In DFE_MODE=3 the tool takes the value provided in DFE_TAP as initial values to obtain the optimized DFE coefficients.

DFE, when used in adapt mode, calibrates the receiver and gives the best DFE coefficients. These coefficients are then used in the fixed mode in simulation to view the  proper eye. Each DFE coefficient in Libero corresponds to 6m in IBIS-AMI DFE tap (tap1 to tap5). Mapping of the coefficients is described in the following table.
Table 8 • DFE Coefficient Mapping between IBIS-AMI and Libero

IBIS AMI Value| Libero Value (Hex)| IBIS AMI Value| Libero Value (Hex)
---|---|---|---
0.006| -1| -0.006| 1
0.012| -2| -0.012| 2
0.018| -3| -0.018| 3
0.024| -4| -0.024| 4
0.03| -5| -0.03| 5
0.036| -6| -0.036| 6
0.042| -7| -0.042| 7
0.048| -8| -0.048| 8
0.054| -9| -0.054| 9
0.06| -a| -0.06| a
0.066| -b| -0.066| b
0.72| -c| -0.72| c
0.78| -d| -0.78| d

Table 8 • DFE Coefficient Mapping between IBIS-AMI and Libero

IBIS AMI Value| Libero Value (Hex)| IBIS AMI Value| Libero Value (Hex)
---|---|---|---
0.084| -e| -0.084| e
0.09| -f| -0.09| f

2.2.2 Libero Flow
Transceiver settings applied using Libero while generating the bit file is explained in IBIS-AMI, page 5. Apart from the earlier explained settings, the Rx model has an  additional option for receiver calibration. This feature is available only in Libero SoC 12.0 and above and not supported by Libero version 2.3 or below.
Select the Transceiver Interface in the Smart Design window to open the configurator dialog box as shown in following figure. The Transceiver supports Enhanced Receiver  Management (ERM), which adds DFE/CDR calibration management and lock-to-data detection capabilities. The ERM is implemented in the FPGA logic inside the XCVR  component. For more information about ERM, see the Enhanced Receiver Management section in Polar Fire and Polar Fire SoC FPGA Transceiver User Guide.

The following receiver calibration options are provided for the ERM operation:

• None (CDR): Select this option if the XCVR is configured as CDR and no CTLE auto-calibration is performed. Static settings are configured by Libero SoC based on data rate and backplane model.
• On-Demand: Select this option to perform calibration on-demand. This option is available for both CDR and DFE configuration of the XCVR. You can trigger  calibration on-demand using CALIB_REQ port as shown in Figure 12, page 17. The CALIBRATING signal is asserted upon CALIB_REQ assertion and de-asserted when the calibration is completed.

• On-Demand and First Lock: This method is an extension to On-Demand calibration option. This allows the customers to perform CDR/DFE calibration either by  toggling the CALIB_REQ pin or after the power on reset.
• None (DEF): DC Offset Calibration of the CDR is performed, however, the DFE Coefficients are set through PDC commands used from the register rather than from  automatic DFE calibration operation. To set the required registers with static values, users must enhance the “section” PDC command to add new attributes. The new  attributes that need to be added are highlighted in the following example PDC file.
  section -port_name LANE0_RXD_N \
  -RX_DFE_COEFFICIENT_H1 20 \
  -RX_DFE_COEFFICIENT_H2 20 \
  -RX_DFE_COEFFICIENT_H3 20 \
  -RX_DFE_COEFFICIENT_H4 20 \
  -RX_DFE_COEFFICIENT_H5 20 \
  -DIRECTION INPUT

The RX_DFE_COEFFICIENT attributes are optional (applied only when Static calibration is selected). These attributes take integer values between 0 and 15. The  corresponding register fields are 5 bits wide in all cases with the MSB bit reserved for sign bit. DEF does not use the DFE calibration routine and requires the user to  carefully select DFE coefficient values. These values can be gathered by the Smart Debug tool or by simulation. When an initial calibration is completed, the performance of  the DFE path can be improved incrementally in the following ways.

• Incrementally Recalibrate Data Eye: This recalibration should improve the data eye for most gradients that typically occur from temperature or voltage changes within the system.
• Incrementally Recalibrate DFE Coefficient: This recalibration performs the DFE calibration in incremental method. The initially calculated DFE coefficient values are  used as the starting values for this algorithm.This results in the reduction of the Calibration time by reducing the number of DFE coefficients that requires recalibration.

Note: Full calibration is always done for DFE. You must select any one of the two options—On-Demand and First Lock or On-Demand—if the transceiver is configured in DFE mode.
In the Signal Integrity View window of I/O Editor shown in Figure 3, page 6, the following Rx settings are selected.

1. Calibration: None(CDR)/On-Demand/On-Demand and First lock/None(Static DFE) options are provided. Please refer receiver calibration modes described above.
2. RX_CTLE : 63 CTLE settings are provided as shown in Table 5, page 13. Users can select any value from IBIS-AMI simulations or recommended values from Ta bleb 4, page 12 or from Table 5, page 13.
3. DFE Mod e: DFE mode is enabled automatically based on the data rate and insertion loss of a channel. DFE values are either auto-tuned in On-demand/On-demand  and First Lock mode or set to values recommended in Table 4, page 12 or set by PDC commands in static DFE mode described in the previous section.

2.2.3 Smart Debug Flow
Follow the section Smart Debug Flow, page 7 for invoking the Smart Debug GUI from the Libero. Select the appropriate receiver settings from the menu as shown in  following figure. Click Apply to apply the settings to Polar Fire transceiver.

CTLE mode: user can select any of 63 CTLE settings from Rx CTLE tab. After selecting the Transmitter and Receiver attributes.
DFE mode: in case the design working in DFE mode, use Optimize Receiver button to auto tune the CTLE and DFE settings. New settings will be displays on the GUI.
In case, user using far end loop back mode, user can generate the PRBS pattern to transfer the data stream. Click Start to start the data out as shown in the Figure 13, page 18.
2.2.4 Illustration
For receiver performance of the IBIS-AMI model, the following design is used as shown in Figure 14, page 19. The Tx is connected to the Rx through, board, 24 inch cables,  package and backplane. The output of the backplane is looped back the Polar Fire Evaluation kit Rx SMAs. Following figure shows the hardware setup.

The equivalent IBIS-AMI simulation setup is shown in the following figure.

The different modes are described as follows.
2.2.4.1 CTLE (CDR mode)
CTLE can be used up to 10.3125 Gbps for short channel as shown in the Table 4, page 12. The following example show the data capture with default Libero settings as well  as optimal CTLE values from IBISAMI simulations at 10.3125Gbps. The system used for the short reach is 5 inch backplane channel along with cables and Polar Fire board traces with following transceiver settings.

• Tx: 400mV, 0dB, 100 Ω

• Rx: 100 Ω
  Libero default CTLE: 5GHz+7.3db and CTLE from Simulation: 5GHz+1.8db

• Data Pattern: PRBS31

The following figure shows the eye Plot from Simulation with Libero default CTLE setting and corresponding eye from ye monitor on Smart Debug

The following figure shows eye plot captured with optimal CTLE setting from Simulation and corresponding eye from eye monitor on Smart Debug.

Note that, eye with simulated CTLE values look better than the Libero default CTLE setting since the Libero default CTLE setting is calibrated to have loss of 6.5dB which is  higher than the loss used in this example. Default Libero settings works with zero bit error however, best value can be found from the IBIS-AMI simulation. In case of  CDR Mode with calibration, Transceiver tunes the best CTLE setting.
CTLE can be used up to 6.8Gbps for long channel as shown in the table 4. Below example show the data capture with default Libero settings as well as optimal CTLE values  from IBIS-AMI simulations at 6.25Gbps. The system used for the long reach is 34 inch backplane channel along with cables and Polar Fire board traces.

• Tx: 1000mV, -6dB, 180 Ω

• Rx: 100 Ω
  Libero default CTLE: 3GHz+6.8db
  CTLE from Simulation: 5GHz+7.3db

• Data Pattern: PRBS31

The following figure shows the eye from simulation with Libero default CTLE setting and Corresponding Eye from Eye Monitor on Smart Debug

The following figure shows eye captured with optimal CTLE setting from simulation and corresponding eye from eye monitor on Smart Debug.

Both the eyes with Libero default CTLE and CTLE from simulation shows similar results.

2.2.4.2 DFE Mode
DFE is used above 6.8Gbps for long and medium reach channel, and above 10.3125Gbps for short reach channel. Below example is based on long channel at 12.5Gbps. The  transceiver tunes the best value with following system attributes.

• Channel: 34 inch backplane channel and 4 inch Polar Fire Evaluation Kit PCB trace
• Tx Amplitude: 800 mV
• De-emphasis: 0 dB
• Tx Termination: 150 Ω
• Data Rate: 12.5 Gbps
• Data pattern: PRBS31

Following figure shows the eye obtained in Smart Debug. The system works with zero bit errors.![Microsemi AC483 PolarFire FPGA Transceiver Signal Integrity

• Backplane](https://manuals.plus/wp-content/uploads/2023/03/Microsemi-AC483 -PolarFire-FPGA-Transceiver-Signal-Integrity-Backplane.png)The blue portion shows the zero bit error rate region.

Glossary

Following are the commonly used terminology in this document.

• TX: Transmitter
• RX: Receiver
• Channel: The connecting medium between Transceiver TX to Transceiver RX is called channel. A channel may contains PCB traces, connectors, cables and backplanes.
• Insertion Loss: The Insertion loss is the loss of signal power resulting from the insertion due to a transmission line (Channel) and is usually expressed in decibels. The  insertion loss is always expressed with respect to frequency. In this document, the loss is expressed at 5Ghz frequency.
• Reach: Reach is a way express the insertion loss of the channel in simple terms. The following terms are used in the document
• Very Short Channel or Very Short Reach: channel loss is less than 2dB
• Short length Channel or Short Reach: channel loss is less than 6.5dB
• Medium length Channel or Medium Reach: channel loss is less than 17dB
• Long length Channel or Long Reach: channel loss is less than 25dB
• Libero: Libero is a software to design and generate the Polarize FPGA programming bit file.
• Smart Debug: A tool in the Libero used for debugging the transceiver online.
• IBIS-AMI: IBIS-AMI is a set of files used to simulate the Polarize transceiver with channel, using simulators such as ADS, Hyperlinks, Systems, QCD and so on. IBIS- AMI simulations helps in finalizing the transceiver settings and sign-off its hardware.

Microchip Proprietary

References

• Microsemi | Semiconductor & System Solutions | Power Matters
• Microchip Lightning Support
• Multiple Results
• Empowering Innovation | Microchip Technology
• Microsemi | Semiconductor & System Solutions | Power Matters
• Microsemi | Microsemi

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