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- From: smithm@liciren.li.co.uk (Martin Smith)
- Newsgroups: sci.electronics
- Subject: Dual opamps
- Summary: Analogue design - the reality between 1 and 0
- Keywords: Operational amplifiers
- Message-ID: <1726@lucifer.UUCP>
- Date: 5 Nov 92 17:24:52 GMT
- Followup-To: Richard Bank's query
- Organization: Lucas Powertrain Systems, Electronic Control Group, UK
- Lines: 36
-
- > ah335@cleveland.Freenet.Edu (Richard Banks) writes:
-
- > I'm building a circuit where I need high gain. I was going to
- > get two single opamps and send the output of one to the input
- > of the other one. But would it be possible for me to just get
- > a dual opamp IC and send the output of one to the input of the
- > other on the same chip?! If this is possible is it a standard
- > practice?
-
- Yes this is perfectly possible, dual opamps were developed
- specifically for reducing the component count and for saving
- space on analogue designs. You can treat them just like two
- separate devices only they're in the same package (it saves on
- decoupling capacitors too). A couple of points to watch out for
- though...You mention high gain, but don't specify whether it's at
- DC, DC + AC, audio, high speed etc. Because of the way opamps
- are manufactured with on-silicon trims to reduce errors inherent
- in the transistors, a single device can have more tweaks than a
- dual crammed into (roughly) the same area of wafer. This means
- that, in general, a single opamp will have better spec's than the
- same architecture fabricated as a dual. Equally, a quad will be
- slightly worse than a dual. Thus if you want good DC precision
- with high gain then two single OP07 devices will probably be your
- best bet, especially if you're pushed for space and intend using
- an 8 pin DIL, where you won't have the offset trim facility
- available.
-
- If you've got any further queries, e-mail me at the address below
- (both work or so I'm told by our computer guy), this is the best
- method of getting hold of me as sci.electronics tends to be quite
- large and I can't guarantee to be able to read all the entries.
- --
- =================================================================
- Martin Smith My opinions are unlikely
- Mail: smithm@eg.lucasauto.co.uk to reflect those of this
- or smithm@liciren.li.co.uk glorious institution....
-