TRF3722: Recommended interface between DAC38J84 and TRF3722 on different boards

Part Number: TRF3722
Other Parts Discussed in Thread: DAC37J84, DAC38J84

Hi,

I have 4 DACs (DAC37J84) on a board and trying to connecting to 8 TRF3722 on another board. I looked at the TRF3722 EVM board, it is using 2 SMA connectors for the In-phase input and another 2 SMA connectors for the quad-phase input. Which means 1 TRF3722 will need 4 SMA. And if I have 8 TRF3722, i would have 48 SMA connectors for interconnection, which have way too many connectors..

1) What is the recommended interconnections between them to have reduction in the number of lines?

2) Can I use "high speed board-to-board connectors" to connect them as differential lines?

3) Or do I need to use balun at the DACs side to do single-ended and then balun at the TRF3722 to reduce the no of coaxial cables if I cannot use the high speed board-to-board connection?

Thanks.

over 6 years ago

0 Keith Barkley over 6 years ago

Guru 35580 points

What is the BW of your I/Q signals? They probably need to be 50 ohm lines, but necessarily SMA's UHF connectors would be fine. 8^)
en.wikipedia.org/.../UHF_connector

You have 4 DACs and 8 modulators. Are they to be switched? connected in parallel?

0 Abdallah Obidat over 6 years ago

TI__Intellectual 775 points

Hi,

I think that you should check out this TI Design (TIDA-00409). It should show how you can interface with the modulator without the SMA connectors, however you should note that in this design the modulator is being interfaced with the DAC38J84.

Regards,

Abdallah

0 Ag over 6 years ago in reply to Abdallah Obidat

Prodigy 30 points

Hi Abdallah,

The design constraint doesn't allow to place the DAC38J84s and the TRF3722 on the same board, unlike the eval module you showed. Hence, asking recommendations on some board-to-board connections?

Thank you.

0 Ag over 6 years ago in reply to Keith Barkley

Prodigy 30 points

They have to be connected in parallel.. 50 to 100 mhz

0 Abdallah Obidat over 6 years ago in reply to Ag

TI__Intellectual 775 points

I think that you should be able to use "high speed board-to-board connectors" for your baseband signal, considering your frequency and bandwidth.

0 Keith Barkley over 6 years ago in reply to Ag

Guru 35580 points

Then you probably want to use 50 ohm resistors at the ADC's and 200 ohm twisted pair transmission lines:
www.allaboutcircuits.com/.../

Put 200 ohm resistors at the IF mixers. Each DAC will see 4 200 ohm impedances in parallel, or 50 ohms.

Otherwise, you will need to use 50 ohm splitters

Actually, standard 100 mil headers should be good enough for the connection at 100 MHz.

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TRF3722: Recommended interface between DAC38J84 and TRF3722 on different boards