Spice Model for ADI 500MHz Four-Quadrant Multiplier Added to my Website (2025 Update)

Only at audio frequencies :-( Further checking shows ridiculously wrong bias currents. Looks like all I managed to cure was Spice spitting out syntax and floating node errors :-(

MY APOLOGIES... DON'T USE UNTIL I ROLL MY OWN. ...Jim Thompson

AD834 is old and expensive!

Did you look at AN-212? It has a bunch of transistor-level detail.

AN-212 is an AppNote. Is there a better multiplier than AD834? I need good performance at 210MHz. ...Jim Thompson

Yes, I believe it is.

Is there a better multiplier than AD834? I

Tons of them. AD8343. ADL5391. Lots more.

Linear Tech. TI.

There are a bunch of IQ modulators that have built-in 90 degree phase shifters that work over a wide frequency range. I can't imagine how they manage that. TRF3701. LTC5588-1. ADL5386.

I'm considering using a fast multiplier, like the ADL5391, for my fast variable-height pulse generator, if I can't find a cheaper way to do it.

On a sunny day (Fri, 16 Jan 2015 18:22:34 -0700) it happened Jim Thompson wrote in :

My AD8346 goes to above 2.4 GHz???

Spice models do not make much sense if 2 cm wire changes everything... :-) measurements, measurements..

Yet Analog Devices keeps on making them.

It's labelled as an active mixer. The AD834 is at least specified as a multiplier.

ADL5391.

At least it's an actual multiplier, and not all that expensive.

TI did take over Burr-Brown and their - not all that quick - multipliers.

Linear Tech might do something quick for a specific application. The last time I poked through the multiplier products I didn't find anything all that interesting.

Thanks. I'll have to find time to review.

I never did quite understand how four-quandrant multipliers worked! We had one or two of these on a vid-proc board at Intergroup. (Video switcher) Diff phase & gain on one input, and I forget what was on the other. Maybe chroma?

It turned out I could get by without fully understanding how the damn thing worked.

Most of the times the girls in assembly either stuffed the caps backwards, or the board's topside got flooded with shorts underneath the parts courtesy of the wave solder machine. :)

Informed by ADI that the AD834 model posted on the web "was not an official release", and I had an immediate need, I rolled my own...

AD834_JT_SUBCKT.zip

on the Device Models & Subcircuits Page of my website.

For the moment LTspice _only_.

Comments most welcome, I want to get these sort of animals modeled correctly. ...Jim Thompson

-- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: skypeanalog | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at

Hello, Where can I find your AD834 spice model today?

Jim Thompson died some years ago - or at least we are fairly sure he did. He got pancreatic cancer, which is pretty reliably lethal, but claimed that it had been detected early, before he stopped posting.

Somebody here may have a copy of his Spice model. I actually used the part, but in a design that never actually made it to production, through we did get a couple of prototypes working. The AD834 and AD835 were remarkably fast, but not all that accurate. Analog Devices would be the place to ask, and they took over LTSpice when they took over linear technology.

They didn't manage to hang onto

On 2025-04-15 08:30, FRAUBRJ wrote:> Hello, > Where can I find your AD834 spice model today? >

No warranties, expressed or implied.

Cheers

Phil Hobbs

Unless one is really picky, a simple BV block can multiply.

Do they come in TSSOP?

Cheers

Phil Hobbs

The BV price is better.

Thanks

I wonder if many peope have a need for an expensive precision analog multipier in real life.

In test sets, probably. Otherwise no.

Cheers

Phil Hobbs (Who last used one in about 1995)

Yeah, that sort of analog computing is a distant memory now.

Test sets? How?

We do still use some MDACs, but we'd go all digital in the future on that product. A 1 Ms/s 14-bit ADC is $2.

A simple test set that needs to compute the power dissipation in a complicated situation, for instance.

Making a measurement ratiometric by dividing out the strength of the excitation.

Test sets sometimes need to do relatively complicated things like that. If you're building one or ten, you'd probably far prefer to spend $50 and be done, rather than spend a week or two designing it like a product.

MDACs are pretty useful sometimes, because all-digital approaches are heavyweight.

For instance, in a control loop, you can get much better bandwidth with a 10 MHz, 14-bit AD5446 MDAC than a 1 MSa/s ADC plus processing plus some normal DAC. It's very common that the resolution required for the loop gain is much less than you'd need for a fully digital solution, so you just use an analog loop and tweak it digitally.

Cheers

Phil Hobbs