1496 (Gilbert Cell Multiplier) Spice Model ??

[Jim Thompson]

Anyone have a 1496 (Gilbert Cell Multiplier) Spice Model ??

I could roll my own but I'm unsure if the I/C models I have, of that
vintage, would be correct.

Thanks!

...Jim Thompson

 

[Joerg]

Hi Jim,

This may be a bit too brief of a model but just in case it suffices for
your application:

http://tardis.union.edu/~hedrickj/eer133/mc1496.lib

I don't know anything about the accuracy or the source though. Thought
you don't use Gilbert cells ......

Regards, Joerg

 

[Mike]

Anyone have a 1496 (Gilbert Cell Multiplier) Spice Model ??

I could roll my own but I'm unsure if the I/C models I have, of that
vintage, would be correct.

The models might be correct, but would they do you any good? When I started
designing ICs, bipolar devices could be designed one by one, and you
started a few years before I did. The design manual for the first process I
worked in was four pages long, and lists geometry-based equations for those
parameters that weren't considered constant. For example:

Rb = (Rcb/Wbc + (2Rb*Lbe/We))/n + K*Rbp*Le/We

Rcb = 19sqrt(Rb)
Rb = base sheet resistance
Rbp = pinched base sheet resistance
n = 1 for single base stripe, 2 for double base stripe
K = 1/(12*(1+(Le/We)^2))

Wbc, Lbe, We, and Le are transistor dimensions.

In all, I have 10 dimension parameters shown for a simple single-base
stripe transistor - for complex geometries we were expected to make our own
models. Every transistor had its own model.

So, the question is, even if you knew your models were good, how would you
know which models to use?

-- Mike --

 

[Jim Thompson]

The models might be correct, but would they do you any good? When I started
designing ICs, bipolar devices could be designed one by one, and you
started a few years before I did. The design manual for the first process I
worked in was four pages long, and lists geometry-based equations for those
parameters that weren't considered constant. For example:

Rb = (Rcb/Wbc + (2Rb*Lbe/We))/n + K*Rbp*Le/We

Rcb = 19sqrt(Rb)
Rb = base sheet resistance
Rbp = pinched base sheet resistance
n = 1 for single base stripe, 2 for double base stripe
K = 1/(12*(1+(Le/We)^2))

Wbc, Lbe, We, and Le are transistor dimensions.

In all, I have 10 dimension parameters shown for a simple single-base
stripe transistor - for complex geometries we were expected to make our own
models. Every transistor had its own model.

So, the question is, even if you knew your models were good, how would you
know which models to use?

-- Mike --

Designing your own transistors disappeared from the scene LONG ago.

There are 61 bipolar model parameters... now-a-days supplied by the
foundry for each device size/shape.

Rolling your own custom device size/shape is generally no longer
allowed.

I have some Semtech models for a process dating from the vintage of
the 1496, and would probably suffice, but I was hoping for a
subcircuit specifically done for the circuit.

...Jim Thompson

 

[Winfield Hill]

Jim Thompson wrote...

Anyone have a 1496 (Gilbert Cell Multiplier) Spice Model ??

I could roll my own but I'm unsure if the I/C models I have,
of that vintage, would be correct.

Why don't you just "wire up" the individual fab transistors
you'll actually be using?

Thanks,
- Win

(email: use hill_at_rowland-dot-org for now)

 

[Jim Thompson]

Jim Thompson wrote...

Why don't you just "wire up" the individual fab transistors
you'll actually be using?

Thanks,
- Win

(email: use hill_at_rowland-dot-org for now)

It's not for one of my custom jobs... I'm just trying to be a good
samaritan and doing an off-the-shelf-component design for a lurker
here.

Now-a-days I deal with bipolars with fTs that were only a wet dream
when the 1496 was designed ;-)

My device library presently includes models for 53 different
processes... all but one no older than 4 years... the Semtech models
are from a late 60s, early 70s, process that's still being used for
"HV" (12V) bipolar chips.

...Jim Thompson

 

[Peter O. Brackett]

Jim et al:

I used to keep all the IC models I needed on one of my wife's 4x5 inch
recipe cards
tucked into my shirt pocket.

But.. those days are now gone forever...

 

[Jim Thompson]

Jim et al:

I used to keep all the IC models I needed on one of my wife's 4x5 inch
recipe cards
tucked into my shirt pocket.

But.. those days are now gone forever...

Didn't it get soggy there in humidity land ?

...Jim Thompson

 

[Mike]

Designing your own transistors disappeared from the scene LONG ago.

I was using 1496's before I even began designing ICs, and I designed many
of my own transistors until around 1990 - many years after the advent of
the 1496. There are only a few transistors in the 1496 - wouldn't the
designers have been more likely to design their own?

-- Mike --

 

[Jim Thompson]

I was using 1496's before I even began designing ICs, and I designed many
of my own transistors until around 1990 - many years after the advent of
the 1496. There are only a few transistors in the 1496 - wouldn't the
designers have been more likely to design their own?

-- Mike --

If by "design" you mean choose the layout, yes, but there were no
models in those days, only breadboards. I've stretched many a base
region to allow a crossover when all we had was single-layer metal.
The "matching" devices were stretched also, even if they needed no
crossover.

...Jim Thompson