AWR1243BOOST: Difference in LVDS 16-bit vs. CSI-2 12-bit complex ADC data

u4564981

Part Number: AWR1243BOOST
Other Parts Discussed in Thread: AWR1243

Per mm-wave SDK user guide, we can select ADC quantization to only 16-bits among 12-bit, 14-bit and 16-bit options. However, for CSI-2 output of the same raw data, the quantization is configured to 12-bits (to support RAW12 format). My question is what's difference in 16-bit quantized data of LVDS and 12-bit quantized data of CSI-2. Specifically:

Is ADC only 12-bit quantized and 14- and 16-bit outputs are merely zero-padded or interpolated results?
If so, can we through out some bits of LVDS 16-bit output to attain 12-bit quantized values? If so, MSBs or LSBs?
Is there any effect on SNR of received signal in going from 16-bit to 12-bit quantization?

Thanks

Arvind

PS: Here are the screenshots of LVDS setting and CSI-2

over 4 years ago

0 Cesar over 4 years ago

TI__Guru*** 148514 points

HI,

The hardware team will be able to get back to you next week

thank you

Cesar

0 Vivek Dham over 4 years ago

TI__Guru 58035 points

Hello ,

For the AWR1243 device you should be referring to the mmwave DFP ( https://www.ti.com/tool/MMWAVE-DFP) .

The ADC data is 16 bit wide. In 12/14 bit modes you can control which of the 12/14 bits you need. Please refer to the "AWR_ADCOUT_CONF_SB" API in the Interface Control Document which is part of the DPF package (https://software-dl.ti.com/ra-processors/esd/MMWAVE-DFP/01_02_06_03/exports/mmWave-Radar-Interface-Control.pdf) . There is a parameter called "Full scale reduction factor" which allows you to choose the bits you want to send out.

regards,
Vivek

0 u4564981 over 4 years ago in reply to Vivek Dham

Intellectual 445 points

Hi Vivek,

Thanks for answering. From the API documentation, it seems the SNR would drop if we try to send out lower number of bits (12 or 14) instead of 16 since we drop the LSBs. Does this also happen with CSI-2 output that sends only 12-bit complex ADC output as apparent from the diagram attached with original post. Or is there a setting to change the number of ADC bits for CSI-2 output as well?

Thanks

0 Vivek Dham over 4 years ago in reply to u4564981

TI__Guru 58035 points

Hello,

The over Rx SNR might not change much since the SNR is mostly limited by front end noise figure and not ADC quantization noise. Unless you are using very low Rx gain settings.

For both CSI and LVDS modes the operation is the same, the 16 bit data can be either sent out fully or can be truncated to 12/14 bits and sent out.

Regards,
vivek

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AWR1243BOOST: Difference in LVDS 16-bit vs. CSI-2 12-bit complex ADC data