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Entry  Tue Mar 1 16:01:14 2022, Paco, Update, Electronics, RFSoC 2x2 board -- setup for remote work & BALUN saga balun_adc1.pngPXL_20220302_001734121.jpg
    Reply  Thu Apr 7 20:33:42 2022, Tommy, Update, Electronics, RFSoC 2x2 board -- setup for remote work 
    Reply  Fri Apr 8 16:03:58 2022, rana, Update, Electronics, RFSoC 2x2 board -- setup for remote work & BALUN saga 
       Reply  Wed Apr 20 14:56:06 2022, Tommy, Update, Electronics, RFSoC 2x2 board -- setup for remote work & BALUN saga 
Message ID: 16767     Entry time: Fri Apr 8 16:03:58 2022     In reply to: 16689     Reply to this: 16790
Author: rana 
Type: Update 
Category: Electronics 
Subject: RFSoC 2x2 board -- setup for remote work & BALUN saga 

Seems like it should be possible to just remove the transformer (aka as a BALUN ... BALanced, UNbalanced), or replace it with a lower frequency part. Its just a usual mini-circuits part. Maybe you can ask Chris Stoughton about this and ask Tommy to checkout some of the RFSoC user forums for how to go to DC.

Quote:
 

After fiddling around with the tone-generators and spectrum analyzer tools in loopback configuration (DAC --> ADC direct connection), we noticed that lower frequency (~ 1 MHz) signals were hardly making it out/back into the board... so we looked at some of the schematics found here and saw that both RF data converters (ADC & DAC) interfaces are AC coupled through a BALUN network in the 10 - 8000 MHz band (see Attachment #1). This is in principle not great news if we want to get this board ready for audio-band DSP.

We decided that while Tommy works on measuring TFs for SHP-200 all the way up to ~ 2 GHz (which is possible with the board as is) I will design and put together an analog modulation/demodulation frontend so we can upconvert all our "slow" signals < 1MHz for fast, wideband DSP. and demodulate them back into the audio band. The BALUN network is pictured in Attachment #2 on the board, I'm afraid it's not very simple to bypass without damaging the PCB or causing some other unwanted effect on the high-speed DSP.

 

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