FAQ: Low Frequency Operating Limit for AD8370 Digitally Controlled VGA

Document created by enash Employee on May 18, 2010Last modified by AndyR on Jan 31, 2012
Version 2Show Document
  • View in full screen mode


What is the low frequency operating limit for the AD8370 digitally controlled variable gain amplifier





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.



AD8370 DC Coupled.JPG