How to output a DC value ?

Hi stefaniecg ,

Thank you for your interest in AD9116. Could you share your schematic, as well as sample scope captures? The output datapath from the DAC to the scope must be free from components that might remove the DC component to be able to observe it (such as filters, baluns, etc.) 

Best regards,
Marco

HI JMMina , good point.

At the output, there is a coupled transformer (MABAES0060) and an opamp (ADA4857-1).

I attach a picture of the schematic. 

Hi stefaniecg ,

You can connect the DAC output to the Op-amp by disconnecting R74 and R78, and connecting R53 , R60, and R59. For your schematic, you can also use the AD9117 Evaluation board (AD9117-DPG2-EBZ) schematic found in the "Helpful Files" section in AD971x / AD911x Wiki User Guide as reference.

Best regards, 
Marco

JMMina , hello

I cannot open the Wiki User Guide you sent, it sends me to a non existent page.

Could you please send a link that is working?

Or let me know how to access it using the link you provided.

Thanx you

Hi stefaniecg, here is the correct link: EVALUATING THE AD9114/AD9115/AD9116/AD9117 AND THE AD9714/AD9715/AD9716/AD9717 DIGITAL-TO-ANALOG CONVERTERS [Analog Devices Wiki]

Thank you for that, i have a question to the schematic: `ad9117-dpg2-ebz_reva_schematic.pdf`, what does `TBD0402` is for a value?

There are so many resistors that have such a description but do not hold a value, i guess that code describes the value?

Specifically, I am interested in knowing the value of R111

Hi Stefanie,

In TBD0402 the "0402" stands for the package size of the smd-resistor. In the layout, there's a footprint for an 0402-package.

"TBD" tpyically means "to be defined". It is often used for soldering options. For example, you could connect an operational amplifier stage to JP3 by soldering an appropriate resistor value to R111. (The actual value may depend on your opamp stage).

In the standard configuration R111 is left open, no resistor is soldered at that position.

That's also described in the bill of materials, which is available on the wiki page. For R111 you find the description "do not install".

best regards

Achim

 JMMina, can you please answer the question above?

Hello, i need support :) JMMina,

According to OpalKelly their SYZYGY-DAC-AD911x board is equivalent to the EVAL-AD9117 board adapted to a AD9116, and the SYZYGY connector.
Thus i have been re-directed here for further questions regarding the schematic (I hope that is correct).

In order to see my DC signals:

I have modified a SYZYGY-DAC-AD911x board according to the table below following **steps 0 to 5**, in order to pass a DC signal trough the OPAMP.
But after comparing it to the EVAL-AD9117 board schematic, failing to simulate it as it is (DC OP simulation does not converge), and observing the AD9116 datasheet: I think i need to execute **step 6**.
The premise is i think your schematic is connecting the DAC to the OPAMP in a _DIFFERENTIAL BUFFERED OUTPUT USING AN OP AMP_ according to pp49/Figure 105 of the AD9116 datasheet.
Thus according to the provided circuit and schematic, i need to connect those resistors in the SYZYGY-DAC-AD911x.

Thus my question:

Q1. Do I need to connect this resistors? i.e. execute **step 6**

Please let me know, thanx

# In reference to schematic of SYZYGY-DAC-AD911x:

| ID | DESIGNATORS | PART | SIZE | VALUE |
| --- | ----------- | ---------------------- | ---- | -------- |
| 0 | Remove | R25, R27, R74, and R78 | 0603 | 0 Ohm |
| 1 | Remove | R28 and R79 | 0402 | 0 Ohm |
| 2 | Remove | C11 and C23 | 0402 | 1u F |
| 3 | Place | R7, R13, R53, and R60 | 0603 | 10k Ohm |
| 4 | Place | R9 and R59 | 0402 | 0 Ohm |
| 5 | Place | C11 and C3 | 0402 | wire |
| 6 | Place | R36, R37, R81, R82 | 0402 | 49.9 Ohm |

 hi can anyone please provide some feedback? EZAdministrator JMMina 

Thank you, highly appreciated.