Yikes, OTA! Blast from the past. What are you going to do with this?
One app on the data sheet shows +-5 supplies.
LT chip? A real LM13600 is fairly cheap.
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An OTA is basically just a differential pair front end and four to six current mirrors in a package. (Unless I've miscounted.) AFAICT, very roughly it should be okay down to about 5*V_BE, i.e. 3 to 3.5V, if you don't insist on all the specs being met. But the actual IC designers on the group will be able to give better info.
Cheers
Phil Hobbs
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Dr Philip C D Hobbs
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Good guess. You need a minimum of +2*Vbe for the positive rail and
-3*Vbe for the negative rail for all mirrors to be happy.
As for linearity I don't know off the top of my head... Tom Frederiksen and Leroy Long did that chip. ...Jim Thompson
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| James E.Thompson | mens |
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I love to cook with wine. Sometimes I even put it in the food.
David, I ran across an AppNote that's essentially the same device...
NNTP-Posting-Date: Sun, 25 Aug 2013 14:04:31 -0500 From: Jim Thompson Newsgroups: alt.binaries.schematics.electronic Subject: LM13600 or LM13700 (From S.E.D) - LM3900_Norton_AppNote.pdf Date: Sun, 25 Aug 2013 12:04:31 -0700 Message-ID: ...Jim Thompson
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| James E.Thompson | mens |
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| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
A Norton amp is a weird mutation that I've yet to find a real use for, unlike OTAs. They're really quite distinct: a Norton is a crappy op amp with a weird asymmetrical input structure and a voltage output, whereas an OTA has a symmetrical input and a current output.
Way back in the day, like 1972, the 3900 had a fairly decent speed advantage over most contemporary op amps, maybe all except the LM318. National pushed it (and its equally dubious successor, the LM359) fairly hard as a building block for stuff like tachometers and filters. Every time I thought of using one, though, its crummy input specs and really horrible noise (especially the 359) brought me up short.
Quite a different matter from an OTA.
Various folks, notably VTC, made much faster OTAs, but they never achieved enough market penetration to survive. I still have a few VA713
70 MHz OTAs in the drawer. TI makes a couple of parts they call OTAs but aren't.
Cheers
Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics
160 North State Road #203
Briarcliff Manor NY 10510 USA
+1 845 480 2058
hobbs at electrooptical dot net
http://electrooptical.net
Certainly a blast form the past. That was the first version Tom Frederiksen and Leroy Long came up with... after they departed SPD for National. ...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
Assuming it's fast enough for the job. It's a nice chip, but it's pretty much audio only. Even the LM13700 is a 2 MHz chip at higher bias currents, whereas the SSM2018 starts rolling off at a couple of hundred kilohertz (Fig 15).
Sometimes it would be really nice to have some of those 50-100 MHz class OTAs like the VA713.
Cheers
Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics
160 North State Road #203
Briarcliff Manor NY 10510 USA
+1 845 480 2058
hobbs at electrooptical dot net
http://electrooptical.net
Section 3.6 look right - DC gain control. I've got a bit to work through now.
I think I still have a LM3900 or two (IC's not individual amps). They were the first op amps I used. While still a school boy I bought one - it was a
3900 or a 741 and the 3900 came 4 to a package. It was just a pity that I didn't realize the significance of the "norton" bit in the description. After I powered it up the insides much have been almost molten by the time I figured out something was wrong. Very sturdy chip though, when I got it figured out (with help) the chip still worked.
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