ADC32RF82: Low level register settings for 2457.6 MSPS, first Nyquist zone, 10x decimation

Phil Leithead

Part Number: ADC32RF82
Other Parts Discussed in Thread: , ADC32RF80

We are using an ADC32RF82EVM to do some testing in preparation for using this ADC on a custom board. We used the 1966.08 MSPS, first Nyquist zone, 8x decimation config files provided in SBAA226C.zip as the basis for our configuration. With this configuration the ADC is working well with our test platform. Unfortunately the wrong LMK part was chosen for our custom board so now we need to run the device at 2457.6 MSPS and 10x decimation. We modified the 2457.6 MSPS, first Nyquist zone, 8x decimation config files from the same zip file for 10x decimation based on the device datasheet. With this configuration the performance with our test platform is degraded. I assume the low level register settings need to be modified as well to achieve the same performance. Can you please provide appropriate config files for this mode of operation?

over 5 years ago

0 Satish Uppathil over 5 years ago

TI__Expert 3515 points

The SBAA226C folder contains a set of files for 2457.6MSPS. So, if you're clocking the device at that rate, you will need to use the files contained in this folder (ADS32RF82/2457p6MSPS). Assuming that the LMFS is kept the same (8821), all you have to do is change the DECIM FACTOR register (001 in DECIMATION page). Is that what you did?

0 Phil Leithead over 5 years ago in reply to Satish Uppathil

Prodigy 50 points

At 1966.08 MSPS we changed the appropriate registers in the config files to give us LMFS = 2441, single DDC, and modified the NCO frequency. For 2457.6 MSPS we started with the config files in the folder you referenced and made similar changes taking the higher sampling frequency into account. In addition to that we changed the DECIM FACTOR register. I noticed the 2457.6 MSPS config files for ADC32RF82 have ADC32RF80 in the subfolder name and match the files under ADC32RF80. I assume this was intended but can you please confirm?

0 Satish Uppathil over 5 years ago in reply to Phil Leithead

TI__Expert 3515 points

I'll have to check about what you noticed about the file names. in the meantime, can you try this config file? you'll have to load the contents of the file called "ADC32RFxx_DDC_10xIQ_2441" first, wait for atleast .6ms and then load the file called "NL". Let me know if this results in better performance.

NL_Config_Nyq1.cfg

ADC32RFxx_DDC_10xIQ_2441.cfg

0 Phil Leithead over 5 years ago in reply to Satish Uppathil

Prodigy 50 points

We tried these files with some minor modifications. We set NCO1 frequency to 491.52 MHz, set Band1 lower/upper-edge frequencies to 375/625 MHz, enabled JESD scrambling and set K=32. Performance appeared to be similar to the ADS32RF82\2457p6MSPS config files from SBAA226C.zip. We also tried the same config with Band1 frequency range disabled since this was not being set in the files you provided, but again the performance did not seem to change.

We also did one other test. We copied the ADS32RF82\1966p08MSPS config files and made only the changes necessary to run 2457.6 MSPS. Once again the performance appeared similar to every other test with 2457.6 MSPS. Is there something else configuration wise you would suggest trying?