=A0 =A0 ...Jim Thompson
Fun for a border-line mental case perhaps. Typical behaviour of a border-line to be at one time intelligent, but at other times having a brain of a two year old :-)
=2E./Klaus
PS My first flame at a NG
Not fun, merely tiresome. You and your coterie are trolls of the worst kind. You are mean and vindictive, but your biggest sin is that you are just plain boring.
Jim
[snip]
Except that runs absolutely counter to the facts...
Right wing talk radio is eminently successful, having no trouble finding sponsors.
On the other hand left wing talk radio had been a consistent failure. Al Franken is a perfect fit for "mean and vindictive"... leftist weenies have NO sense of humor. Even by stealing from the Girls and Boys Club of NY, the show still failed.
Left wing talk radio has been SUCH a failure that the leftist weenies want a LAW to require equal time for leftist weenies... that is public-supported leftist weenie radio.
Keep that in mind come election time, kiddies ;-)
...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |
America: Land of the Free, Because of the Brave
Exactly what do you think NPR is?
Leftist weenies are all for it.
-- Keith
=A0 =A0 ...Jim Thompson
In other words, right wing radio shows tell their audience what they want to hear, unimpeded by pesky facts. And the message they are putting over suits people with loads of money, who are happy to subsidise the propaganda.
Constrained by reality .... fiction always sells better than fact. Telling people that they have been lied to - found any good weapons of mass destruction recently? - does tend to come across as mean and vindictive, while good-old-boy-lies can be folksy and entertaining.
I saw Dubbya on TV tonight claiming that Iran was the world's leading spender on international terrorism. Considering the number of dead people heaping up in Irak as a consequence of a thoroughly misjudged and very expensive occupation initiated by Dubbya himself, some might think that there was another - even stronger - contender for that dubious honour.
It's called education. Right-wingers hate it, and certainly don't like paying taxes to support it, because it provokes voters into asking embarassing questions,
As out of touch with reality as ever.
-- Bill Sloman, Nijmegen
Oh, you mean he should be helpful like you?
All YOU ever do in this group is smother it in off-topic posts and then ask others to do your work for you, for free, while charging your clients for it.
You should look in the mirror before talking about others.
-- Pay no attention to that man behind the curtain...
Bwahahahaha! It is rare indeed when ANYTHING useful is ever posted here.
Some experts users in the area I was unfamiliar with have responded usefully.
...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |
America: Land of the Free, Because of the Brave
I have no problem whatsoever with "being written off" by the likes of you.
Thanks, Rich
So, what did you finally buy? Inquiring minds want to know ... :-)
And no, this time we won't ask what circuit you built.
-- Regards, Joerg http://www.analogconsultants.com/
I'm on hold while I await further experiments by the client, but it certainly looks promising to use small MOS devices to cascode large photodiodes into TIA's.
...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |
America: Land of the Free, Because of the Brave
So far I've only once cascoded with a FET and back then it was ye olde
2N7002/BSS123 (but still followed with a BJT). Later only bipolar. Then the fiberoptics part of my biz life became easier, lots of speed but really low-C photodiodes.I am sure you've read Phil Hoobs' paper but in case other haven't seen it yet:
For low-C work the newer dual-gate FETs are nice but I believe your stuff is low frequency and I don't know how they behave down there noise-wise. This would be the BF998 (they really messed up their links now):
-- Regards, Joerg http://www.analogconsultants.com/
If you follow Phil Hobbs advice, you'll use small BJT transistors instead. But check your PD currents, at very low currents this approach is not optimal, IMHO.
Yes. There are some fantastic low noise devices out there. Even the old BCX70K that John Larkin once pointed out is a great performer in the sub-audio range. Not so for many FETs.
-- Regards, Joerg http://www.analogconsultants.com/
Phil and I loosely keep in touch... he even knows who I'm working with right now ;-)
...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |
America: Land of the Free, Because of the Brave
My simulations and the client's experiments are showing lots of harmonic distortion with bipolars, but not with MOS.
...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |
America: Land of the Free, Because of the Brave
Will this be biased by a current source (like, 1 mA) that parallels the photodiode? Transconductance of a MOS near cutoff isn't what I'd like to see in a cascode situation. I had a similar application in mind for some current-source gizmo, but couldn't find PMOS in anything except high-current switches. The old 3N141s in my junk box looked about as good as the modern NMOS I could find...
Phil solves that by prebiasing the emitter of the BJT and then removing the current at the collector side. In fact, at very low currents, it's the matching of these two currents, which Phil gets with two resistors, that creates a DC current error, and is the reason I rarely use his cheap low-noise PD-amplifier trick. But you should evaluate it.
I rarely care about the exact value of the DC photocurrent, but if it's important you can get it by putting a bypassed sense resistor in the anode lead of the PD. Comparing the two measurements lets you take out the current imbalance to any accuracy you like.
Cheers,
Phil Hobbs
I was thinking one could use fast mmics to amplify the ac part of a pd signal, and pick off the current at the other, bypassed end of the diode to get the dc term, amplify that separately, and combine to get a final dc-coupled response. The final combining stage is interesting (we'd want a good wideband 50 ohm source, dc to 10 GHz maybe) and matching the lf crossover would be a nuisance.
Maybe if things get slow...
John
That would be a pretty useful gizmo.
Another approach would be to dc couple into the MMIC, use a sense resistor that's nominally the same value as the MMIC's transimpedance, and use a slow loop to force the MMIC's dc output to track the voltage across the sense resistor. Alternatively, you could do the same thing with a slow autozero sampling scheme, which wouldn't mess up the LF response of the amp. Of course, if your signals are typically small modulations on top of big DC pedestals, you may run out of swing on the MMIC. You also have to put up with the MMIC's flicker noise.
Cheers,
Phil Hobbs
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