ADS54J42: ADS54J42 SNR?

HENRY JUNG

Expert 2030 points

Part Number: ADS54J42
Other Parts Discussed in Thread: DAC3482, , ADS54J40

Dears.

We are developing ADS54J42.

We have an ADS54J42 problem on the board.

Band Width : 60Mhz,

LMFS=2242

Decimation : 2

Lane Rate : 5.5Gbps

We need help and solutions.

The figure below shows the ADS54J42 ADC input with matlab captured by FPGA.
The ADC clock is 276.48MHz and the IF is 207.36MHz Center.
The difference (-6.9) - (-60.1) = 53.2 is about 18MHz from the center when singleton is input.

The figure below shows the ADS54J42 input looped to the DAC3482 and measured using the MXA.
At 18MHz from the center, the difference is 53.3.
The data sheet(14page) is about 70.
What's the problem?
Problems with ADS54J42 configuration?

Thank you.

over 6 years ago

0 jim s over 6 years ago

TI__Guru* 91947 points

Henry,

In this mode, you need to select either low pass filter mode or high pass filter mode. In each case, your signal of interest (207.36MHz) will fall in the transition band. See the attached file for more info regarding this. You also have a wrong lane rate. It should be 2.7648Gbps with this setup. I have also attached the ADC config file I used for this setup. The plots show that when using the high pass filter mode with your setup, the usable bandwidth is between roughly 139MHz and 202MHz. If it is critical that you be able to sample data at 207.36MHz, you will have to change your sample rate.

Regards

Jim

ADS54J42_Fs_276.48MHz_LMFS_2242.pptx ADS54J40_2x_dec_highpass_2242.cfg

0 Brian2001 over 6 years ago

TI__Intellectual 2750 points

Henry,
I have sent your question over to an engineer that will take a look at it.
Regards,
Brian

0 HENRY JUNG over 6 years ago in reply to Brian2001

Expert 2030 points

Dears.

We have an ADS54J42 problem on the board.
The exact conditions of our test results are as follows.
We need CFG file support.

Band Width : 120Mhz,
Lane rate : 5.5296bps
ADC data rate : 276.48MHz
Fs : 552.96MHz
Fin : 207.36MHz
LMFS : 2242
DEC : 2x
DEC FILTER : LPF

Register Value
6900
01 32
00 80
06 0F
31 0A
32 0A

6800
4D 80
41 12
52 81
72 08
44 3E

Thank you

0 jim s over 6 years ago in reply to HENRY JUNG

TI__Guru* 91947 points

ADS54J40_2x_dec_lowpass_4222_Fs_552.96M.cfgHenry,

The attached config file works with the TI EVM using your settings.

Regards,

Jim

0 HENRY JUNG over 6 years ago in reply to jim s

Expert 2030 points

DEAR.JIM

Loading a CFG file from ADS54J42EVM will not PLL lock it.

Should I use the ADS54J40_2x_4222 file in HSDC-Pro?

The test results are as follows.

Our LMFS is 2242.

Can you support HSDC ADS54J40_2x_2242 files?

The difference between the SNR and EVM values of the document.

The figure below is based on the guide document.

EVM LOAD

"LMK_Config_Onboard_614p4_VCO1"

"ADS54J40_LMF_8224"

Test Source is 187.5Mhz, 8dBm.

SNR is not 70dBFs.

Why does it differ from the Datasheet?

The test results are as follows.

Thank you

0 jim s over 6 years ago in reply to HENRY JUNG

TI__Guru* 91947 points

Henry,

I may have sent you the wrong file. If you still plan on using the settings sent to us shown below, please try the config file attached.

Band Width : 120Mhz,
Lane rate : 5.5296bps
ADC data rate : 276.48MHz
Fs : 552.96MHz
Fin : 207.36MHz
LMFS : 2242
DEC : 2x
DEC FILTER : LPF

Regards,

Jim

ADS54J40_2x_dec_lowpass_2242.cfg

0 HENRY JUNG over 6 years ago in reply to jim s

Expert 2030 points

Dear.JIM
You need an HSDC-Pro file to test the attached file.
I do not have 2242.ini in HSDC-Pro.
I need an HSDC-Pro file to test the attached file.
Please tell me how to test.
Thank you.

0 jim s over 6 years ago in reply to HENRY JUNG

TI__Guru* 91947 points

6082.ADS54J42_LMFS_2242.zipHenry,

Files are attached.

Regards,

Jim

0 HENRY JUNG over 6 years ago in reply to jim s

Expert 2030 points

Dear. JIm

We input 187.5 MHz and 8 dBm into the ADC with the signal generator.

SNR does not appear in customer Board, as shown in Figure 10 of the datasheet.

Our SNR is 55dbfs.

What is the solution?

Thank you

0 jim s over 5 years ago in reply to HENRY JUNG

TI__Guru* 91947 points

Henry,

Is this still an issue? If so and it is a custom board, can you send the schematic so we can take a look at it?

Regards,

Jim

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ADS54J42: ADS54J42 SNR?