DAC39RF10 datasheet(197/232 Pages) TI2

197 / 232 page

Offset Frequency (Hz)

1x102

1x103

1x104

1x105

1x106

1x107

1x108

-180

-170

-160

-150

-140

-130

-120

NRZ DEM/Dither off

NRZ DEM/Dither on

DES2XL DEM/Dither off

DES2XL DEM/Dither on

fCLK = 10.24GHz

Figure 9-5. Phase Noise vs Offset Frequency at 1GHz

There are 3 small disadvantages of DES2XL and DES2XH modes to be aware of:

1. the attenuation of the signal in the transition band of the DES interpolation filter between 0.4*FCLK and

0.6*FCLK

2. An increased latency of 97 clock cycles. or 9.7ns with a 10GHz clock, due to the DES interpolation filter

3. An increase in power of 250mW with a 10GHz clock, due to the DES interpolation filter

9.1.4 Eye Scan Procedure

The PHY layer contains features for generating eye diagrams. A variety of different modes are supported (see

ES register for list of modes). The following sections describe how to generate eye-scan data from the part and

some approaches for building an eye-diagram.

1. Configure the part for JESD204C operation by following the steps in the Startup Procedure for DUC Mode.

Return here after setting JESD_EN=1. Eye-scan can be run with JESD204C bitstreams, but can also work

with general PRBS input stimulus. Eye-scan is run on all enabled physical lanes simultaneously.

2. Program ES to the desired eye-scan mode.

3. If ES is less than 8, you must program ESVO to the desired voltage offset. For other modes, the eye-scan

logic automatically adjusts the voltage offset of the eye-scan sampler.

4. Program ESPO to the desired phase offset.

5. Program ES_BIT_SELECT to a value from 0 to 19. Eye-scan analyzes every 20th received bit (decimate-

by-20). ES_BIT_SELECT adjusts this decimation phase. For random stimulus, this does not impact the

results. If the input has repeating patterns, this can affect the results.

6. Program ESLEN to the desired number of samples. Higher settings give more consistent results.

7. Set ECOUNT_CLR = 1 then set ECOUNT_CLR to clear the error counter. This step is recommended, but

can be skipped if desired (e.g. to add up counts from multiple eye scan runs). This can also be skipped if

ECOUNT won’t be used (for modes with ES of 8 or greater)

8. Program ESRUN = 1 to start the scan.

9. Poll ESDONE until ESDONE returns 1 for each of the lanes you want to run eye-scan on.

10. If the selected eye-scan mode modified the eye-scan voltage offset (inner/outer/average modes), read

ESVO_S to get the inner/outer/average eye boundary. For other eye-scan modes, read ECOUNT to return

the number of mismatches (or matches) recorded.

11. Program ESRUN = 0.

12. Return to step 2 to run another eye-scan data collection process. The receiver can remain enabled during

multiple iterations of steps 2-12.

There are two basic approaches to build an eye diagram using the eye-scan feature.

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DAC39RF10-SP, DAC39RF10-SEP

DAC39RFS10-SP, DAC39RFS10-SEP

SBAS932A – MARCH 2024 – REVISED FEBRUARY 2026

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Product Folder Links: DAC39RF10-SP DAC39RF10-SEP DAC39RFS10-SP DAC39RFS10-SEP

DAC39RF10 Datasheet(PDF) 197 Page - Texas Instruments

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