Paper on reducing 1/f noise in amplifiers

Am 05.05.2015 um 23:20 schrieb Phil Hobbs:

No, but by now it should be common knowledge if it's any good.

Places to go:

nist.gov, search for Fred Walls, Ferre-Pikal, timefreq group, 1134.pdf "origin of 1/f PM and AM noise in Bipolar Junction Transistor Amplifiers"; there is more.

regards, Gerhard

I just looked at it. No special magic...

Quote:

"GOOD LOW-NOISE PERFORMANCE at low frequencies is difficult to achieve in an amplifier without resorting to careful selection of the input transistors. Such selection is, at best, an expensive process for discrete-component circuits and a nearly unobtainable luxury for monolithic integrated circuits. The circuit of Figure 1 has superior low-noise performance at low frequencies. It consists of a Darlington pair of transistors and a dc current source connected to the emitter of the input transistor. This current source allows the independent adjustment of the small-signal transconductance of the input transistor. When the transconductances of the two transistors are equal, the excess output noise is nulled. In a typical realization described below, the noise performance is an order of magnitude better than that of either transistor alone."

They then show how to make a differential pair of the same circuit.

Steve

I'm interested in reducing the 1/f noise of pHEMTs, which besides low V_A is their only vice. An order of magnitude improvement in the 1/f noise would reduce their noise corner from 10 MHz to 100 kHz, a fairly startling improvement.

Of course the mechanism is different, so the BJT trick may well not work.

Cheers

Phil Hobbs

Received a copy from the estimable John M in Scotland. Interesting bit of work, but only a couple of pages long--about $15 per page from the ever-generous IEEE. Thanks, John!

Cheers

Phil Hobbs

Some Engineering student or professor on campus goes around exercising his freedom of speech. He pops up A4 posters reading:

"IEEE Transactions on Opportunity Hoarding"

Steve

What annoys me is that virtually all of this research is funded by the taxpayer, so we get to pay twice :-(

Maybe a lawsuit is in order? ...Jim Thompson

The abstracts are written to make it unclear whether the paper might be useful. You have to buy the whole thing to find out. It's better to assume that it's not useful, which is the general case.

Den onsdag den 6. maj 2015 kl. 16.09.39 UTC+2 skrev John Larkin:

it's 2 pages with four graphs and two rough schematics

here anyone can walk in to university library and see it for free, or if you are on a university network just download it

-Lasse

Same here, but my spending an afternoon driving to the city and back would cost the customer a lot of 31 buckses. There's an outfit called DeepDyve that lets you take a squint at the paper for 6 bucks or so before buying it, iirc, which is better but still annoying.

Cheers

Phil Hobbs

Unfortunately that title doesn't narrow it down very much. ;)

Cheers

Phil Hobbs

Certainly a lot of it is pure gibberish. But I have a PhD buddy who gets me copies (for free) of anything I find interesting. ...Jim Thompson

The Optical Society is more generous--I get 50 or something downloads included with my $100 per year membership, which is a lot more reasonable.

Cheers

Phil Hobbs

I can go to the nearby UC Med Center library. For a min of $20, I can buy a printer card, which lets me print things for $1 a page. They have all the major journals online. I can look at them on a PC, and print just the pages I want.

I do that on an occasional binge basis, maybe once a year, when I need to learn something new. Last one was Fourier Transform Mass Spectroscopy. I might research sub-Abbe-resolution fluorescent microscopy soon.

This is also how the IEEE Digital Library program works, except it's more like $40/month. It's violently annoying to pay that for research that was largely taxpayer-funded in the first place, but it's also a hard habit to break.

For one-off requests, try /r/scholar on Reddit.

-- john, KE5FX

I think the IEEE probably doesn't own the copyright on the US Govt research. When I worked for a company and submitted a conference paper to ISSCC they made me sign something to assign the copyright to them, like this form:

You will notice the section for US and UK government employees to sign - where they concede that where the funding body won't give the IEEE all of their rights, the IEEE is still happy to publish the paper anyway. Admittedly the IEEE can still coerce authors into handing over right to a lot of papers that are only indirectly government-funded.

If you could compile a database of all of those papers that the IEEE does not own the rights to, and put those papers online, I doubt the IEEE could do a thing about it, and may get in trouble if it tries.

Anyway I don't intend to sign any more if the IEEE's copyright assignment forms, if they ever do want to print something of mine in future.

I would like for a referendum of IEEE members to be held, about whether papers over 5 years old should be automatically open-access to members, and whether the papers should also be open-access to the public. I think most members would want at least older papers to be open-access, and most corporate subscribers to IEEE journals would keep paying for immediate access. I would like such a referendum to be held, not because I think the IEEE would obey the outcome, but because their reaction would demonstrate whose interest the IEEE management works for.

Chris

In physics, we have the Arxiv preprint site, where you can have a look at a lot of papers in publication. It's run sort of like the Royal Society--you have to have a member submit the paper for you, which keeps down the spammers and cranks.

It also goes a long way towards solving the fast vs slow journal problem in hot fields. (I don't read that many recent physics papers.)

Cheers

Phil Hobbs