ad8336 gain

Hi nalluri ,

It seems that there's an issue with your posted problem since it is only a gray color. Can you post your question again or reply to this thread your question?

Thank you!

Regards,

Mae

• The total gain varies with a voltage of -600mv to 600mv  as per attached Screenshot.
• In our design We are terminating Vgneg pin with positive 1.25v supply and Vgpos voltage through DAC 
• We are planning to give DAC voltage from 650mv to 1850mv to Vgpos pin to achieve gain of  -600mv to 600mv from the formula  Vgain=Vgpos-Vgneg.
• We are connecting our circuit in non inverting configuration with pre amplifier gain as 4*.and total gain is up to 46db.please find the attached files for info.
• in our design we getting only 8 to 10db gain .preamplifier gain is coming properly but output is improper.if you suggest any changes it will helpful for our design.
• our input signal range is from -60db to -10db and freq is upto 20-40MHz .

Hi nalluri ,

Can you also include some scope shots of the input and output? 

Thanks,

Mae

Is there any possibility to limit the frequency above 20MHz signal in the above design.in the above design we are setting Vgain as 0 and 16db gain we are expecting in our circuit. the gain is coming .but for higher amplitude values i,e above 80mVpp1-20Mhz is ok but 30-40Mhz freq range the signal is not proper .can you help what is the reason behind it.?

Hi,

In AD8336 preamplifier output some offset is there.after it is giving to VGA also it is not removing that offset .finally my IC output is coming with offset is it expected behaviour of AD8336.

if it seems to be expected then how can i remove that offset it is effecting the total my TX path.

with increase of frequency from 1-40 MHz VGA output is increasing what is the reason .if that is also expected where these are mentioned datasheets .Clarify?

Reply as soon as possible.

it is one of my VGA output voltage.why it is not properly biased?