Re: Op-amp design: Bipolar or Cmos

linnix wrote:

On Jun 4, 1:20 pm, Joerg <notthisjoerg...@xxxxxxxxxxxxxxxxxxxxx>
wrote:

linnix wrote:

On Jun 4, 11:39 am, Joerg <notthisjoerg...@xxxxxxxxxxxxxxxxxxxxx>
wrote:

linnix wrote:

On Jun 4, 11:12 am, John Devereux <jdREM...@xxxxxxxxxxxxxxxxxx> wrote:

linnix <m...@xxxxxxxxxxxxxxxxxx> writes:

On Jun 4, 10:41 am, Joerg <notthisjoerg...@xxxxxxxxxxxxxxxxxxxxx>
wrote:

Jim Thompson wrote:

On Mon, 04 Jun 2007 09:09:07 -0700, linnix <m...@xxxxxxxxxxxxxxxxxx>
wrote:

We are in the process of building some op-amp ICs.

Who is "WE"?

I found a reference design and layout of a bipolar op amp.
However, the author says that cmos op-amps are more popular
in the real world.

CMOS OpAmps are more "popular" because they're cheap. They're also
generally low power, resulting in high noise, high VOS, and low
gain-bandwidth product

Questions:

#1 Anybody got a cmos op-amp design and layout to sell or license?

No. But I can design one for you once you have a set of
specifications.

#2 Anybody able to port from bipolar to cmos?

Yes. I started designing when there was ONLY Bipolar

#3 What are the drawbacks to stay with bipolar, other than powers?

None. Better offset, better gain-bandwidth product, better slew-rate,
higher output power capability, higher operating voltage capability.

Often lower cost as well, simply because they are older and the sheer
volume is so high. I mean, where can you get a rocket like ye olde uA733
for around 30 Cents in CMOS?

We figure the incremental costs of 10 to 20 cents, cheaper than the
external packaging costs. Of course, we have to eat the $30,000 NRE.

At that rate I'd look around and see if I could use a commercially
available jelly been part.

Have you looked at the price of "ye olde" LM358?

Yes, that's what we are designing out.

If I can have the layouts please (GDSII or CIF files). The dice need
to be fitted into the wafer in exact places, but not necessary
efficient usages.

Not the greatest
opamp perhaps, but then I don't suppose the ones inside a
"system-on-chip" are that great either. If that is what you are doing
- it's still not clear to me.

The Opamps I've seen on S0Cs so far were IMHO, as Archie Bunker would
have put it, lousay.

Yes, the reference design says a gain of 10. But we have plenty of
silicon spaces for as many stages as we need.

Sorry about the misunderstanding. I am talking about adding an op-amp
inside a chip. It will be part of a wafer cap anyway, so only
minimum additional processing costs. It will save bonding cost and
PCB spaces.

Many opamps can be purchased as die.

Dice are not good enough. They need to be at exact places of the
wafer, and bonding out on the other side.

Even if the data*** doesn't say
so it is worth contacting the manufacturer about it. If you want to save
the bonding and pour it into your chip design you could ask them about a
license. I mean, these days they are licensing complete micro
controllers, why not a simple opamp? Or maybe Jim has one in the hopper
where he owns a right to resale of the IP.

Yes, how about it, Jim?

I got a free bipolar reference design, so just looking for additional
options.

Don't have time to go through it again right now but IIRC even the old
Geiger, Allen, Strader "VLSI Design Techniques" had CMOS examples in
there. Might have to lay it out but in IC design that is usually done by
layouters,


That's just as expensive, especially in learning curve.


If nobody in your company has ever done that, yes. But seriously, I'd use an outside chip designer in that case. We had done the same, although our ultrasound company was about 300 employees.


not the actual (more expensive) designers.


We are a nano size company, so the designers and layouters are the
same. The IC and PCB layouters also program the uC as well.


Those places are often seriously fun to work at. The smaller the better.

--
Regards, Joerg

http://www.analogconsultants.com
.

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