AD8370 dc coupled with dual supplies

Q. How much current do we supply the negative supplies when we operate the AD8370 in Dc coupled mode as per figure 51? -------------------------------------------------------------------------------------------------------------------- A. In the configuration in figure 51, I would expect all of the current to flow through the negative supply. Total supply current = 82 mA. Attachments:

Low Frequency Operating Limit for AD8370 Digitally Controlled VGA

Q. What is the low frequency operating limit for the AD8370 digitally controlled variable gain amplifier ------------------------------------------------------------------------------------------------------------ A. As long as the input common mode level is set correctly, there is no low frequency limit and operation all the way down to dc is possible. A dual dual supply of +/-2.5 V can be used along with input and output common mode levels of 0V (see Figure 51 on page 18 of the Rev. A data sheet). To address situations where dual supplies are not convenient, a second option is possible. The AD8138 differential amplifier is used to translate the common-mode level of the driving source to midsupply, which allows dc accurate performance with a ground-referenced source without the need for dual supplies. This application is described in more detail on pages 18 and 19 of the Rev A data sheet.