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Observed 6.8dB delta in amplitude flatness of AD9208

Question asked by Dwijen.Pandya on Dec 26, 2017
Latest reply on Jan 15, 2018 by Dwijen.Pandya

Hi, 

Hi,

I am using AD9208 for one of my application. I am using AD9208-3000EBZ+ADS7-V2EBZ for the evaluation.

 

The AD9208 datasheet mentions the 3dB bandwidth of the ADC as 9GHz.

When I measure power on the ADC across the frequencies, I have got following values.

The measured power varies around 6.87dB across the frequencies.

 

Is this expected?

Since 3dB BW is 9GHz, The power measurement flatness for freq < 9GHz should be lower than 3dB. Is this understanding correct?

 

Freq (MHz)

RF Power Set on Keysight MXG Sig Gen (dBm)

Meas Power on ADC (dBFS)

0.5

-40

-56.44

1

-40

-56.12

1.4

-40

-55.82

2

-40

-55.59

2.5

-40

-55.8

2.9

-40

-56.4

3.5

-40

-56.94

4

-40

-57.54

5

-40

-58.67

6

-40

-61.48

6.5

-40

-62.46

Max

-55.59

Min

-57.54

Delta (dB)

6.87

 

 

Regards,

Dwijen Pandya

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