X-Received: by 10.157.11.98 with SMTP id p31mr5713672otd.33.1486518044865; Tue, 07 Feb 2017 17:40:44 -0800 (PST) MIME-Version: 1.0 Path: csiph.com!weretis.net!feeder6.news.weretis.net!feeder.usenetexpress.com!feeder1.iad1.usenetexpress.com!216.166.98.84.MISMATCH!border1.nntp.dca1.giganews.com!nntp.giganews.com!r185no50837ita.0!news-out.google.com!g47ni28qta.0!nntp.google.com!peer01.iad!feed-me.highwinds-media.com!news.highwinds-media.com!spln!extra.newsguy.com!newsp.newsguy.com!drn From: Winfield Hill Newsgroups: sci.electronics.design Subject: Re: Difference Amp. Date: 7 Feb 2017 17:40:36 -0800 Organization: Rowland Institute Lines: 25 Message-ID: References: NNTP-Posting-Host: p480e97bc5a2798d5d40e240ff9a1514622ff97e5e640269f.newsdawg.com User-Agent: Direct Read News 5.60 X-Received-Bytes: 1278 X-Received-Body-CRC: 4220321042 Xref: csiph.com sci.electronics.design:446720 John Larkin wrote... > >> Hmm that might be my only question. Would you >> use these instead of an opamp and 0.1% R's? > > A difference amp, with tracking laser-trimmed > resistors inside, is fairly cheap. Right. These parts aren't going to disappear. Most of the popular versions shown in our 1989 2nd edition are still going strong, and will for decades to come. > One cool part is AD8130, 270 MHz, interesting > architecture. The high-frequency gain and good CMRR is nice, but since it uses the cancellation of two differential BJT g_m stages as its input, it isn't a precision part, like a fine op-amp + 0.01% matched resistors. -- Thanks, - Win