Comments on: Specifying an op-amp http://www.ladyada.net/rant/2006/02/specifying-an-op-amp/ afowejfaiwuehfakjnfa Tue, 06 Jan 2009 06:12:02 +0000 http://wordpress.org/?v=2.6.3 By: ajk http://www.ladyada.net/rant/2006/02/specifying-an-op-amp/#comment-4488 ajk Tue, 11 Mar 2008 18:00:41 +0000 http://www.ladyada.net/rant/?p=8#comment-4488 I would like to mention that the AD8655 actually has a thermal noise floor of 2.7nV/rtHz. I would like to mention that the AD8655 actually has a thermal noise floor of 2.7nV/rtHz.

]]> By: tober http://www.ladyada.net/rant/2006/02/specifying-an-op-amp/#comment-12 tober Tue, 21 Mar 2006 17:26:01 +0000 http://www.ladyada.net/rant/?p=8#comment-12 This is a nice example and I suspect you're aware of the following but I wanted to mention a couple things for the potential edification of other readers: 1. <a href="http://www.amazon.com/gp/product/0521370957/sr=8-1/qid=1142960834/ref=pd_bbs_1/104-7432314-0749561?%5Fencoding=UTF8" rel="nofollow">The Art of Electronics</a> also contains some good information on op-amp selection. 2. In a somewhat demanding amplifier design such as the one in your example, it is sometimes also worth considering a two-stage design. Sometimes two op-amps of somewhat lesser specs (purchased as a dual monolithic device) cascaded appropriately work as well as and cost less than a single fancier one. You generally wouldn't be able to get out of whatever noise requirement you have (for the first stage anyways) but the requirement for gain-bandwidth product of each op-amp is reduced appreciably. This is a nice example and I suspect you’re aware of the following but I wanted to mention a couple things for the potential edification of other readers:

1. The Art of Electronics also contains some good information on op-amp selection.
2. In a somewhat demanding amplifier design such as the one in your example, it is sometimes also worth considering a two-stage design. Sometimes two op-amps of somewhat lesser specs (purchased as a dual monolithic device) cascaded appropriately work as well as and cost less than a single fancier one. You generally wouldn’t be able to get out of whatever noise requirement you have (for the first stage anyways) but the requirement for gain-bandwidth product of each op-amp is reduced appreciably.

]]>