New production 3080 OTAs

[ElectricDruid]

Alfa in Latvia have cloned the CA3080 as the AS3080E. Well, sort of. The "E" stands for "extended" and they've added the linearisation diodes of the LM13700 so you can use those if you want to. There were two unused pins on the CA3080, so they can do that and still have a chip that is pin-for-pin compatible with the original. Nice touch.

Datasheet here:

http://www.alfarzpp.lv/eng/sc/AS3080E.pdf

Incidentally, the parameters seem to match the "A grade" CA3080A (the selected CA3080s) and some show improvements over even that better chip. For example, worst-case offset drops from 2mV to 800uV, although the typical figure is the same. Notably, the Gm linearity is extended by a further decade (so 1:10,000 instead of 1:1000).

Original CA3080s have been getting harder and harder to find, and more expensive too, so some cheap new ones sounds like a good idea. Now I'll be able to design stuff that only uses a single OTA! I never liked to before cos I couldn't stand to waste half a 13700!

[Scruffie]

I never liked to before cos I couldn't stand to waste half a 13700!

The amount of time I've wasted trying to come up with uses in a circuit for a superfluous OTA halve...

Neat, although I'll still hold out hope for a CA3094.

[ElectricDruid]

Neat, although I'll still hold out hope for a CA3094.

What's the advantage of the CA3094? I don't think I've ever even seen one, let alone used it.

[imJonWain]

Funny, I was just looking at their 3280 chip and thinking of ordering a few for some experiments.  Is there a US source for their 3080?

You've seen Rochestor electronics also makes a 3080AE version and pretty cheap too especially in bulk.

[StephenGiles]

Neat, although I'll still hold out hope for a CA3094.

What's the advantage of the CA3094? I don't think I've ever even seen one, let alone used it.

From memory, the tricks available from a CA3094 depend on which pin is connected to +v. There was an Ehx paper on this chip which I used to have - Julia Truchess may still have a copy. I'm currently on holiday in Fen country near to Ely, where it is currently very wet and very windy, but I'll do a search when I return home.

[PRR]

I'm sure it has been mentioned: Rochester Electronics ran a wafer of '3080s and Small Bear is a good source for small to medium quantity. This would be "original mask" (or good fax) on "vintage process" (almost inevitably better than when the '3080 was born).

[Scruffie]

Neat, although I'll still hold out hope for a CA3094.

What's the advantage of the CA3094? I don't think I've ever even seen one, let alone used it.

It has a darlington like the 13700 but gives you access to both the current sink and source output so it has tricks up its sleeve and can help save a lot of space in a circuit design taking the place of an inverting op amp output.

[skyled]

Now we can't complain about Phil and Dino using them in DeadEndFX projects anymore 

[11-90-an]

Sorry for my inexperience, but how do I order the CA3080? Should I send them a email?

I guess I'm used to the "add to cart" in other online shopping platforms...

Sorry, again...

[Kipper4]

Great news. Love that chip.

[ElectricDruid]

Sorry for my inexperience, but how do I order the CA3080? Should I send them a email?

I guess I'm used to the "add to cart" in other online shopping platforms...

Sorry, again...

They don't really sell to end consumers directly - their shipping is too expensive to make it worth it for a start, and an EU VAT number helps too. I've only just been notified that this chip is available, so I expect it'll turn up in the usual resellers (including the Druid shop!) in due course - Small Bear, Thonk, Banzai, etc etc. Erica Synths have probably got it already, since they're in Riga too and have been closely involved with Alfa.

[Fenton Bresler]

Can anyone shed light on how the output can be both single ended and push-pull (as per the datasheet)?

[11-90-an]

I do hope it would be cheaper, though... the ones in stock now range from 1.90 to 6.00usd!

Glad to hear that it might be available in the druid shop.. wanted to pick up some of yer other chips in there...

[PRR]

> how the output can be both single ended and push-pull

What does "single ended" even mean?? If a rope has one end, it has to have another end!! (What I used to say when untangling microphone cables.)

Yes, ONE meaning is Fender Champ: one solitary 6V6 yanks the speaker. But a glance at the circuit shows that's not the case here.

[ElectricDruid]

Just to say that I've been playing with this new chip a bit recently, and I have to say that it's not like the genuine CA3080 at all.

It's much better than that!!

I did a ring-mod circuit with it, and I was able to trim it to get it *really quiet* with practically no modulation feedthrough at all. Now, I've *never* managed that with an OTA before, let alone with the old 3080. I was impressed.

I also did a simple VCA, and it's easy to get going. I think it's got less hiss that the old ones used to. They were always noticeably noisy, whereas this is noticeably quiet.

So, all in all, it might have the same pinout and number, but this is very definitely a modern chip. It's really good. I recommend you grab a few to play with from your favourite supplier of silicon goodies.

[PRR]

To be clear: you are endorsing the Alfa AS3080E? (The Rochester is also "new production" I think.)

> this is very definitely a modern chip.

Going back in '3080 history I re-read this:
"..these CA family of products were developed by RCA on a very old and obsolete fab process that is long since been discontinued ... We have been living on wafer stock. Today the wafer stock has been depleted...." Intersil corp., 2005
http://www.till.com/blog/archives/2005/06/last_of_the_ota.html

So RCA made way too many 3080 wafers back in 1970, and for the next 35 years ALL genuine 3080s came out of that one bucket? Sliced and diced to metal ceramic or plastic as fashions changed, but all 1969 fabrication? And while there was SOME really-clean Silicon in 1969, I don't think of RCA in that context.

[ElectricDruid]

Yes, I'm talking about the Alfa AS3080E. I don't know about any Rochester new-production-from-old-wafers stuff. Haven't seen any of it.

The IP for a simple chip like this is pretty well known by now, so Alfa have just produced a clone using whatever their current process is. And then they added the linearisation diodes from the LM13700 as well. The specs come out at least as good as the best CA3080's (the "A" grade") and better in several important cases.

I posted because better specs are one thing, but in my opinion this new chip is audibly better than the old one, and that's what *really* counts.

I'd be interested to hear other people's view on it, if anyone else has had a chance to play yet.

[jubal81]

Other than repairing old equipment, what advantages would this chip have over an LM13700?

[Rob Strand]

The IP for a simple chip like this is pretty well known by now, so Alfa have just produced a clone using whatever their current process is. And then they added the linearisation diodes from the LM13700 as well. The specs come out at least as good as the best CA3080's (the "A" grade") and better in several important cases.

Looks like a cool chip.   The low noise and low offset are a big bonus.   With modern production techniques there's no excuse to do otherwise these days.

From the internal schematic it looks like they have kept the "one diode drop" off the negative rails for the IABC pin, which keeps compatibility with the CA3080.

FWIW, there was a CA3280, sort of a dual CA3080 but better and with the linearizing diodes.  I can't remember the voltage drop for IABC.

[ElectricDruid]

Other than repairing old equipment, what advantages would this chip have over an LM13700?

You don't finish up wasting an OTA! Also, it takes up less space.

For the Engineer's Thumb (or ten other compressors based on OTAs), for example, you only need one OTA. The rest of the chip is redundant.

FWIW, there was a CA3280, sort of a dual CA3080 but better and with the linearizing diodes.  I can't remember the voltage drop for IABC.

Yeah, Alfa have cloned that one too - the AS3280. I haven't really played with it, but Small Bear have them. The original CA3280 was considered the best of the OTAs by many. The Rev.3 Prophet 5 uses it as the final VCA in each voice, for example. It might well be a better choice if you need a dual OTA.