Circuit Contest - Last Day

Nope. Just stop acting like a TURD and I'll stop calling you one.

...Jim Thompson

It's also noisy at low gains, figs 24, 25. Barry first attenuates the input signal then amplifies it back again.

Hmmm.... Sounds like a little of TokaMundo has rubbed off on you!^)

In my sonar case the low-gain noise is not an issue... low gain equals high signal handling capability, so the SNR is still good.

...Jim Thompson

I read in sci.electronics.design that Mark Zenier wrote (in ) about 'Circuit Contest - Last Day', on Wed, 2 Nov 2005:

I do so HATE having to explain. (;-)

Both; it's a PUN (check - Czech, Swede - swede). Geddit?

Hello Jim,

Does it work like the AD603 ladder or is it a stack of the usual Gilbert cells?

Only if you are at liberty to say, that is.

Regards, Joerg

Hello Jim,

IOW, Gilbert "de luxe" ;-)

Regards, Joerg

Hello Jim,

That is where chip solutions make life so much easier. Us discrete designers have to find cheap enough PIN diode pairs and generate a pilot carrier that allows tracking yet won't interfere with the passband signals. Or run the pilot straight through the amp. But as a reward we're gitten all the dynamic range we wants ;-)

The AD603 has an interesting attenuator up front that maintains good dynamic range. But that thang has become so expensive that I haven't used one in a design in years. They might still be under patent protection for that attenuator.

Regards, Joerg

Hello Win,

True. It was intended for ultrasound, or at least its forefather AD600 was. The main concern there is wall echoes of blood vessels which are huge at echoes nearby. A Gilbert multiplier just doesn't cut it for those jobs.

My favorite scheme is controlled resistance at the collector or drain, usually via PIN diode. But not 40dB worth of range in a single stage.

Regards, Joerg

Right, hence Barry's design decision. But I'd like to see an electronic attenuator with that architecture but with a say -20 to +20dB gain range.

I was just pedantically pointing out that a vanishingly small number of Americans would know about the root vegetable, as it's a parochial English usage.

I'm afraid I got it the first time. Uff Da. (Since we have more Swedish immigrants than Englishmen in my part of the country, implying they were "turnips", well ... ).

Mark Zenier snipped-for-privacy@eskimo.com Googleproofaddress(account:mzenier provider:eskimo domain:com)

Barry's cutest trick is the staggered sections of asymmetric differential (BJT) pairs... left device bigger than right paralleled with right bigger than left.

Analyse it sometime, you'll like it... I wish it wasn't patented ;-)

...Jim Thompson

Hello Win,

The AD603 is -11dB to +31dB in its wide bandwidth configuration. It wouldn't be a big deal to migrate that into a chip that does -20dB to

Considering that I played with the AD600 around 1992 the patent may not have that much life left in it. But I doubt that there'll be much competition coming once it expires. It is such a small market and the really cost critical designs are likely going to remain discrete anyway.

Regards, Joerg

Yes, I was on top of that as soon as he came out with it, grabbing all the info I could, patents, etc., and modeling the result. There is an interesting tradeoff between performance and complexity. By performance, I mean the little humps in the log plots of gain-vs-voltage. As for the patent issue, I'm free to design with the idea for our internal use, as anyone else is, but the idea's complexity and matching requirements make that impractical (it's too bad there isn't an analog equivalent of cPLD or FPGA chips). You don't have that problem, but your only practical use for it is commercial. So all either of us can do is admire the idea on paper.

I guess you still can have Jim design a chip for you for internal use.

Well, I grew up in Minnesota, and there, "Swede" pretty much means "Your neighbor's ancestor.".

There's turnips, there's kohlrabi, and there's rutabaga, and as you go down the density scale, there's carrots, and wood.

You can bite into a kohlrabi, almost as easily as you could bite into a potato, or an apple. And, heh, heh, the flavor of a kohlrabi is kind of "sweetish". Guh-hyuk! .

A turnip is only a fat albino carrot.

But a rutabaga - now, that's the yellow one - I've never seen a rutabaga that's as orange as a carrot, but biting into one would be like biting into a carrot that's covered with wax and has a radius of about 3" (7.5 cm). To make a rutabaga edible, you have to cook it for about an hour.

But, DAMN! They're tasty! They have that "adult" flavor, like Brussels sprouts.

Gotta go make some lunch now. ;-)

Cheers! Rich

Hello Jim,

I don't remember the patent date but since I played with the AD600 in the early 90's this patent protection is bound to run out in the not too distant future.

Regards, Joerg

I read in sci.electronics.design that Mark Zenier wrote (in ) about 'Circuit Contest - Last Day', on Fri, 4 Nov 2005:

One of my aims in life is to teach Merkans about other languages. (;-) Besides there are a number of people here who aren't Merkans.

The thing with orange flesh is only called a swede in England, I think In Scotland, it's a turnip or neep. I'm not sure what if any difference there is between a rutabaga and a turnip or swede.

Mangold-wurzel, anyone? That 'wurzel' is German or Dutch in origin, I'll bet.

You should have subtly signalled that, then. F'rinstnace, 'Just czeching that you know we call them turnips or rutabaga in Leftpondia.'

Is that some sort of Welsh?

I didn't invent the name 'swede' for the vegetable or the name 'Swede' for a person from Sweden.