TI's 36V Bioplar SiGe Process OPA211 OPA827

That looks like a sweet process. The reduction in 1/F noise is impressive if their example of the closest competitor is accurate. The unfortunate commercial reality is the number of sockets that require this level of performance are limited in number and volume. The higher GBW may open them up to more non-audio applications. If they can deliver this level of performance at competitive pricing to former technology they will win many design-ins on general principles.

Nice parts. IMO makes the benefit of rolling your own quite modest. Especially compared to special purpose opamps that often trade one parameter for another. Utilization of an improved process doesn't appear to have any downside other than perhaps cost. Did EET article speak to long term budgetary pricing relative to existing process? I suspect TI would like to milk that cow (charge a premium) for as long as they can, as you mention they didn't report a great quarter.

JR

[quote author="mediatechnology"]Actually it was an ad and I can't find pricing anywhere.

It could be that this process (and production line) is one they borrowed from RF. I seem to recall hearing SiGe and wireless a lot in the same sentences over the years. So it might be that when wireless fab utilization goes up these parts will get put on the back burner like the rest of the Burr Brown op amps have been.

I'd be very reluctant right now to design in anything sole-sourced by TI right now no matter how good they are until they can consistently deliver product.[/quote]

Agreed the cellphone-wifi market is probably driving the technology. Low noise is also important in RF receiver front ends. Back in the good old days I was burned by mature parts going away too. The double edged sword of overly conservative design.

One painful new part availability story involved a kit article I wrote back in the '70s that won the cover of Popular Electronics. After the orders started piling up (that I had to ship within 30 days thanks to FTC regulations), I frantically started expediting my parts that were already on order. The distributor who told me the parts were in stock months earlier when I placed my order, explained that by "in stock" they meant at die level, and the parts still had to travel to Malaysia to get packaged, and then ride the slow boat back here. Arghhhh.

JR

Looks intriguing.

I am a bit puzzled by the bias current number on the FET amp though; plus and minus 3pA. One would imagine it would be one or the other sign, although perhaps they have some input protection going on whose leakage current dominates.

I recall when I corresponded with Barrie Gilbert and, although a bit impatient with my questions, he mentioned some work at AD involving bipolar heterojunction parts with betas of >100,000. I think that was SiGe in fact.

I'm particularly impressed that they are this far along, for a relatively new technology, in getting the flicker noise down. Remember how long it took with MOSFETs?

However, I'm not ready to abandon discretes just yet for every application. The thermal issues, that is, signal-induced self-heating, are still difficult to manage on a tiny chip.

As far as the package availability: I fear we must all learn to handle SMD. If I can manage it pushing 60 then you younguns ought to be able to. Breadboarding is a challenge I'll admit. And you can throw out your white prototyping fixtures with the little jumpers and such (good riddance I say :grin: ).

[quote author="bcarso"]Looks intriguing.

I am a bit puzzled by the bias current number on the FET amp though; plus and minus 3pA. One would imagine it would be one or the other sign, although perhaps they have some input protection going on whose leakage current dominates.

I recall when I corresponded with Barrie Gilbert and, although a bit impatient with my questions, he mentioned some work at AD involving bipolar heterojunction parts with betas of >100,000. I think that was SiGe in fact.

I'm particularly impressed that they are this far along, for a relatively new technology, in getting the flicker noise down. Remember how long it took with MOSFETs?

However, I'm not ready to abandon discretes just yet for every application. The thermal issues, that is, signal-induced self-heating, are still difficult to manage on a tiny chip.

As far as the package availability: I fear we must all learn to handle SMD. If I can manage it pushing 60 then you younguns ought to be able to. Breadboarding is a challenge I'll admit. And you can throw out your white prototyping fixtures with the little jumpers and such (good riddance I say :grin: ).[/quote]

The +/- bias current spec might also be the result of some kind of first order correction circuit, if it isn't just protection clamps.

I can work on my SMD stuff with about two pairs of reading glasses and a magnifier. When I was visiting my CM a few weeks ago he talked about hand populating a bunch of 01x02 parts for a customer who screwed up and approved an incorrect no-pop list. I don't even want to think about stuff that tiny.

I wonder if high volume users will stop at some point short of that or keep pushing the envelope smaller and smaller.

JR

[quote author="bcarso"]As far as the package availability: I fear we must all learn to handle SMD. If I can manage it pushing 60 then you younguns ought to be able to. Breadboarding is a challenge I'll admit. And you can throw out your white prototyping fixtures with the little jumpers and such (good riddance I say :grin: ).[/quote]
We all will have seen things like these:


We could spend a few hours a year to stuff a pile of these with various SO-devices and just continue as if the world was still completely thru-hole.

The prices I've seen so far are silly though. Anybody in China listening ? :twisted:

So the white boards don't need to be abandoned yet, but don't know if that's really an advantage indeed :wink:

Regards,

Peter

[quote author="clintrubber"]
We could spend a few hours a year to stuff a pile of these with various SO-devices and just continue as if the world was still completely thru-hole.

The prices I've seen so far are silly though. Anybody in China listening ? :twisted:

So the white boards don't need to be abandoned yet, but don't know if that's really an advantage indeed :wink:

Regards,

Peter[/quote]

I dismissed my white-board prototypes when I started noticing effects from the interline capacitance. Sometimes beneficial as opamps don't put the minus input next to the output by chance, but you want prototypes to closely mimic reality. I suspect the capacitance is only low pFs but I recall it messing with an old digital circuit (probably some gate propagation delay timing tweak using low drive current CMOS).

JR

When I breadboard I like the Twin Industries stuff with plated-through holes and a plane on one side. The problem is I tend, out of force of habit, to make mechanically robust connections before I solder. These then become very inconvenient if the damn circuit doesn't work as I expect! And this material doesn't accomodate SMD well at all, unless those adapter things are used. In those cases I just build on the top of a ground plane board with the SMD chips on their backs and use wirewrap wire, mostly. It is a pain.

For the pad-per-hole stuff I use teflon tubing when the point-to-point connections are in danger of shorting out to one another. I like the absence of meltback and carbonization. It's harder these days to get tubing in multiple colors and I have more trouble seeing what's going on anymore as well. But then most of the time the simulations are pretty representative, so I do less and less breadboarding as it is.