AD9635 with ADA4927 as driver

Hi Claus,

Thanks for your interest in AD9635!

Yes, that is feasible. You can check the schematic in the design and integration files section of the user guide link below and check the optional active path. However, the driver used is ADA4930 but you can configure that one if you want to use ADA4927 or ADA4938.

EVALUATING THE AD9655/AD9645/AD9635 ANALOG-TO-DIGITAL CONVERTERS [Analog Devices Wiki]

I suggest to use the ADI DiffAmp Calc so that you can simulate your desired driver.

ADI-DiffAmpCalc | Analog Devices

Regards,

Xavier

Hi Xavier,

Thanks for your quick reply.

I looked at the schematic for the EVAL board as you suggested, and tried to simulate the ADA4930 design in the DiffAmpCalc. The design around the ADA4930 seems to be based on Input Common-Mode Adjustment with Resistors as described in the ADA4930 data sheet page 22. I don't think DiffAmpCalc can simulate that design approach, or am I missing something?

Anyway, I believe I get the idea of how to configure an ADA49xx.

There is not much information in Wiki or the design and integration files about how to use the optional active path (the ADA4930) on the EVAL board. I have pieced together the schematic for the network between the ADA4930 and the ADC from EVAL board. I have removed all the DNI components. The schematic in the picture is what remains. 

Are the components in the blue box necessary? The ADA4930 already provides a common-mode voltage and I would remove R412 and R413. What is the purpose of R433/R434? Maybe they are just part of the RLC place holders for a potential filter, but they are not marked DNI as the rest of the place holders?

Regards,

Claus

Hi Xavier,

Thanks for your quick reply.

I looked at the schematic for the EVAL board as you suggested, and tried to simulate the ADA4930 design in the DiffAmpCalc. The design around the ADA4930 seems to be based on Input Common-Mode Adjustment with Resistors as described in the ADA4930 data sheet page 22. I don't think DiffAmpCalc can simulate that design approach, or am I missing something?

Anyway, I believe I get the idea of how to configure an ADA49xx.

There is not much information in Wiki or the design and integration files about how to use the optional active path (the ADA4930) on the EVAL board. I have pieced together the schematic for the network between the ADA4930 and the ADC from EVAL board. I have removed all the DNI components. The schematic in the picture is what remains. 

Are the components in the blue box necessary? The ADA4930 already provides a common-mode voltage and I would remove R412 and R413. What is the purpose of R433/R434? Maybe they are just part of the RLC place holders for a potential filter, but they are not marked DNI as the rest of the place holders?

Regards,

Claus

Hi Claus,

I apologize for the late reply.

I made a mistake for the comment I made for this and yes, you are right. To correct, you do not need the blue box when employing VCM at ADA4930.

Regards,

Xavier