AFE7950: Regarding the NCO signal of TX A

Yake Li

Part Number: AFE7950

Hi，

I set the NCO to 1800MHz and cannot measure this signal on the spectrometer.

I only opened TXA and TXB, and all other RX and FB were turned off. JESD in FPGA has not been opened yet. Do I need this feature to measure a frequency of 1800MHz on TXA?

I just want to measure a frequency signal on TXA to verify if my AFE chip is working properly. Is there any way? Because the AFE chip on my device is only connected to the FPGA SPI interface, I cannot use the LATTE。 software.

over 2 years ago

0 David Chaparro over 2 years ago

TI__Genius 17891 points

Hi Yake,

To check the DAC output without the JESD link you can put the DAC into a test pattern mode. The function below will put the DAC channels into a constant test pattern and the outputs will be the NCO frequency.

for i in [0,1]:
	for j in [0,1]:
		AFE.JESD.DACJESD[i].dacJesdConstantTestPatternValue(1,j,0,16384,0) # enable, channelNum, bandNum, Ival, Qval

Regards,

David Chaparro

0 Yake Li over 2 years ago in reply to David Chaparro

Prodigy 120 points

Hi David,

Thank you. I can already measure the NCO of txA-txD above the spectrum.

Now I need to test if rxA-rxD can work properly? How can I test RX without JESD link?

0 David Chaparro over 2 years ago in reply to Yake Li

TI__Genius 17891 points

Hi Yake,

The only way to test the ADC, without the JESD link, is to put the AFE in JESD loopback mode. In this mode the ADC JESD data is looped back to the DAC.

Please see the following app note for additional information.

https://www.ti.com/lit/an/sbaa525a/sbaa525a.pdf

Regards,

David Chaparro

RF & microwave

RF & microwave forum

AFE7950: Regarding the NCO signal of TX A