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DAC38J84: Output DC coupled

lionel rodriguez

Prodigy 30 points

Part Number: DAC38J84

Dear,
I want to use a DAC38J84 as a wideband AWG to drive IQ inputs (differential) of a PSG E8267D.
BW : 1GHz [-500M / +500M]
SFDR > 65dBc
Sampling rate : 2.5GHz
On the DAC38J84EVM, Ti implemented RF transfo but I want a DC coupling.
I would like to know if I can implement the design detailed below.
Regards.
Lionel Rodriguez

over 4 years ago

0 Kang Hsia over 4 years ago

TI__Guru* 78174 points

Hi,

You may refer to below app note, section 4 for DC coupled suggetions:

0 lionel rodriguez over 4 years ago

Prodigy 30 points

Thanks for your answer

I have another question.

I bought the dac38J84_evm board to bench my project.

But the SFDR is very bad -48dBc (hd2)

Setting :

JESD204B - 6.144Gbps

Sample rate 614.4 MSPS (FPGA)

Interpolation : 2

DAC sample rate : 1228.8 MSPS

Output fréquence : 20MHz

Internal oscillator

What is the problem ?

Regards

Lionel

0 Kang Hsia over 4 years ago in reply to lionel rodriguez

TI__Guru* 78174 points

Hi,

I see you have opened a new thread. We can use this new thread to discuss. I have forwarded to appropriate folks to answer. Thanks.

https://e2e.ti.com/support/data-converters/f/data-converters-forum/984649/dac38j84evm-dac38j84---sfdr-out-of-specifications

-Kang