AD9681 balun stage

Hi Hoang,

Thanks for your interest in AD9681. Even though that balun's datasheet rating is 4.5MHz, it works well at lower frequency. How low of a frequency do you need?

Thanks,

Doug

I test with 500kHz square of arbitrary signal generator. I met the low frequency loss and phase shift. 

How is about 500kHz or 1MHz?

Hi,

I thought 500kHz would be OK, but if you have tried it and it does not meet your need, the AD9681 evaluation board also has pads that can accommodate a Mini-Circuits ADT1-1WT+, which is rated down to 400kHz.

You would need to remove the two MABA-007159-000000 and install the  Mini-Circuits ADT1-1WT+.

The AD9681 evaluation board schematic is here: wiki.analog.com/.../08_039100b_cam.zip

Thanks,

Doug

Thank you Dougl. Is there any examination you test with it? 

Hi,

We use single tone sinusoid as an initial test signal for many of our tests. I don't have specific test conditions for the Mini-Circuits balun but you could try a 500kHz single tone test as a starting point.

At some point the impedance of the 0.1uF AC coupling capacitors could be an issue for you to be aware of.

Doug

Hi Dougl, 

I replace the balun stage to Mini - circuits but the result I got was the same with the older one at 500kHz.

Here is my result. square waveform at 500kHz.

I try to see the voltage spectrum. 

Could you tell me the problem and recommend what should I do?

Thank you.

HOANG

Hi Hoang,

How does the waveform look if you apply a 500kHz sinusoid?

Thanks,

Doug

Hi Dougl,

Sinunoid looks well. 

Another question. Why was my signal voltage probe at SMA connector pin decreased by 2? example: 2Vp-p Sinunoid signal generator --> at SMA connector pin: 1.2Vp-p 

Thanks,

HOANG

Hi Dougl,

Sinunoid looks well. 

Another question. Why was my signal voltage probe at SMA connector pin decreased by 2? example: 2Vp-p Sinunoid signal generator --> at SMA connector pin: 1.2Vp-p 

Thanks,

HOANG