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Common mode matching between AD9253 and AD8352

Question asked by veera on Sep 17, 2012
Latest reply on Sep 18, 2012 by UmeshJ

Hi,

 

We are using IF sampling ADC (AD9253) in our system. ADC driver, AD8352 is used to drive this ADC.

In the datasheet of the ADC, it is shown that it is better to drive the input signal with the common mode voltage of 0.9V. How to make sure that ADC driver output is centered around 0.9V?

 

Should we just connect Vcm pin in ADC to ground through 0.1uF cap (to get 0.9V Vcm) and connect this Vcm pin to the Vcom pin in AD8352? Will this scheme work? Or should we only use transformer based coupling as shown in datasheet of the ADC?

 

The frequency of operation is 140MHz with BW of 40 MHz. In this case is it even necessary to think about common mode voltage, since our signal has zero DC component?

 

Thanks in advance.

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