Cascode substitutions

Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> Wrote in message:
> On 01/31/2016 06:39 PM, bitrex wrote:
>> Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> Wrote in message:
>>> On 01/31/2016 04:43 PM, bitrex wrote:
>>>> Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> Wrote in
>>>> message:
>>>>> On 01/31/2016 03:42 PM, bitrex wrote:
>>>>>
>>>>>>>
>>>>>>> You've already said that you're a moral relativist, so there's
>>>>>>>   no use appealing to your better nature.  ;)
>>>>>>
>>>>>> True, but it doesn't seem to stop people from trying...
>>>>>
>>>>> A lot of moral relativists are much better than their principles,
>>>>> and I hope you're one.  The principles themselves are so bad that
>>>>> it's scarcely possible for someone to be worse.
>>>>>
>>>>> I try very hard to deal only with straight shooters.  I've had to
>>>>> fire customers who weren't, and I certainly wouldn't knowingly work
>>>>> with someone whose moral ideas were controlled by his own
>>>>> convenience.
>>>>>
>>>>> Cheers
>>>>>
>>>>> Phil Hobbs
>>>>>
>>>>
>>>> The weird thing is, regardless of my moral relativism, I seem to
>>>> generally behave in a moral fashion. But I couldn't tell you exactly
>>>>   why. Guess I had those messages drilled into me real good and I
>>>> can't handle the cognitive dissonance. I catch spiders and gently put
>>>> them outside.
>>>
>>> Which does make you better than your principles, at least part of the
>>> time.  You might want to inquire--as a matter of some urgency--where
>>> that higher moral law (for that is what it is) that judges your
>>> intentions comes from.
>>
>> A sociopathic rapist murder goes to Heaven because he accepts
>>   Christ on his deathbed, but an atheist who lived a moral life to
>>   the best of their abilities within the structure of their society
>>   is damned, because they didn't accept that someone died for their
>>   sins (of which they likely committed fairly few.)
> 
> Where do you get the idea that any of us is permitted to speculate on 
> the eternal fate of another?  Christ Himself explicitly forbade it. 
> That's what "Judge not, lest ye be judged" means.  It isn't about 
> behaviour--we're expected to be sensible about _that_--but we can't 
> possibly set bounds to the mercy of God.
>>
>> lol, want talk about universal concepts of "fairness"!
> 
> Again, I don't know anybody who advances the view you recite.  Do you?
> 
> Cheers
> 
> Phil Hobbs
> 

Sure, they're usually called "evangelicals."

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On 01/02/16 11:18, Phil Hobbs wrote:
> On 01/31/2016 06:45 PM, Clifford Heath wrote:
>> On 01/02/16 10:00, Phil Hobbs wrote:
>>> On 01/31/2016 04:43 PM, bitrex wrote:
>>>> The weird thing is, regardless of my moral relativism, I seem to
>>>> generally behave in a moral fashion
>>> Which does make you better than your principles
>> What makes you the expert in someone else's moral principles?
>> Sheesh, that arrogance surely knows no bounds.
>
> Sorry?  It's okay with you if I rob you blind because I think it's okay?

Whoosh. You completely missed the point.

You made the comparison "better" in regard to bitrex's "principles".
How do you even know his principles? You merely assume that they are 
worse than his self-described behavior because you assume they must be 
worse, because he's a moral relativist. Is it possible that you don't 
even see the non-sequitur here?

>>> One of the many problems with that view is the immense agreement between
>>> people of all eras and all places on what is and is not OK.
>> So therefore there's something extra-physical, mystical, magical,
>> non-material, from which all moral truth descends? That's a total
>> failure of logic.
> I didn't say that.  You keep going on about mystical magical stuff,
> whereas I'm talking about the basic structure of existence.

Yes you did. You told bitrex to "inquire where that higher moral law 
(for that is what it is) that judges your intentions comes from" and 
then went on to assert that it must exist because every society thinks 
there must be one.

Guess what? It doesn't come from anywhere but human imagination. We 
imagine how nice it would be if *everyone else* acted like that, and try 
to make it so by all means possible.

>> Could it be that folk just recognize that they need to try to contribute
>> to making and maintaining the kind of world they'd like to live in? That
>> they have a responsibility - even a selfish one - to maintain a moral
>> order?
>
> No, it couldn't.  Otherwise nobody would do the right thing when nobody
> was looking.  Some people do.

No, they don't. Everyone acts in their own selfish interest for their 
own convenience anyway. The only difference is that some people define 
convenience in terms of an imaginary standard of uprightness, of which 
if they don't loudly protest their support, the others of their social 
circle will disapprove of them... and that would actually become 
inconvenient.

More rational folk admit that this absolutist approach to granting 
self-approval, in order to gain societal approval, in order to maximize 
convenience for oneself (but without admitting that's what's happening), 
is nothing more than a mind trick.

Religion is the only stage-play that relies on the actors denying to 
themselves they're even acting in a play. How can audience and actor 
co-exist in one undivided soul? No wonder it creates such perversions.

Clifford Heath.

On Sun, 31 Jan 2016 18:16:49 -0600, "Tim Williams"
<tiwill@seventransistorlabs.com> wrote:

>"John Larkin"  wrote in message 
>news:ecvsab1s93c4v3joh7imn68pb5ngthqg6k@4ax.com...
>>The real fork in the road is whether it needs to be wideband. A 100
>>MHz amp is a lot different from a DC-to-100 MHz amp. Narrowband, you
>>can tune out parasitics, which is how people get tubes and mosfets to
>>work at a GHz.
>>
>>Wideband gets more interesting.
>>
>>What's it for?
>
>Well, including DC basically means replacing inductors with complementary 
>PP, or CCSs.  And bandwidth is just the span from "near DC" to whatever 
>the HF cutoff is.

Some people use "LF" instead of, literally, DC coupled. You know what
I mean.

>
>You can tweak a "narrow" amp into a "wide" one by playing with the filter 
>topology and impedances.

And gain drops as you do it. Lots of RF amps will drop below unity
power gain as you try to widen their bandwidth. That's why people are
using exotica like GaN to make really wideband amps.

>
>Suppose you start with a conventional narrowband amplifier, using parallel 
>tuned resonators, and matched with whatever means apply (L-match, L or C 
>dividers, tapped coils..).
>
>At each resonator, the ratio of resonator Zo to system Z gives the Q 
>factor and therefore width of that stage (give or take stacking resonators 
>for flatter bandpass, sharper skirts, and slightly stretching (peaking) 
>the bandwidth limits).
>
>As you reduce Q (assuming you are able to, by increasing Z and L, and 
>reducing C; normally C has a minimum due to the amplifying device, which 
>trades off with Z as an approximate GBW limitation), the bandwidth spreads 
>out, and the impedance ratios available via reactive matching networks get 
>closer to 1.  So you start needing more transformers than reactive 
>networks for matching, and resonators with impedances closer to the device 
>or system impedance.  Which tend to get less extreme and therefore easier 
>to construct.  Series-parallel transformations can be reversed, giving 
>traditional filter topologies, like series resonant links between parallel 
>resonant tanks, instead of coupled resonators.
>
>As BW rises still further, Q < 1 means R dominates over X for much of the 
>band, and the networks aren't really resonators at all anymore, so you can 
>pull them apart, using large value RFCs to supply bias, and using LPF 
>network design to manage the device capacitance.
>
>At this point, it's usually relatively trivial to convert the remaining 
>RFCs and coupling capacitors into DC-friendly R or CCS parts, at the usual 
>cost of efficiency.  Transformers being the one exception, for which you 
>need to change much more (supply voltages, transistor types..).  (This 
>being one of the fundamental limitations of vacuum tubes -- high load 
>impedance.)

For a given device, you generally have a limiting GBW, so wideband
tweaks eventually kill all the gain. RF mosfets and HF mmics are
usually internally tuned, to get gain at high frequencies, and there's
nothing you can do to make them wideband.

Low noise figures are assiciated with tuned circuits, too.




>
>So along this spectrum, I expect to design an amplifier in one of the 
>latter categories: treating HP and LP behavior separately, using matching 
>if necessary.
>
>"Wideband" means different things to different people.  I've seen planar 
>circuits claiming 1GHz "wideband" performance.  Sure, that's pretty wide 
>in the usual scheme of things, but out of a 20GHz center frequency, that's 
>a puny 5%... a Q of 20...  To me, I mean a circuit where the LP and HP 
>behavior is roughly independent, and the HP is optional (so that it may 
>truly include DC).
>
>Speaking of tubes -- they work just fine at high frequencies.  6C4 is a 
>rather unimpressive type, but an oscillator built with one (running at a 
>modest, say, 100MHz) will show harmonics out to nearly 1GHz!  It's the 
>only nonlinear element in the circuit, so all those harmonics are indeed 
>due to changes in electron flow occurring that fast.  Of course, those 
>harmonics are in the -80dB range, so it's not like there's much left up 
>there.  (It's also relatively unusable, because electrode self-resonances 
>occur in the 300MHz+ range.)  But the physics is real.  Planar triodes of 
>course went out to about 10GHz, and TWTs are still around with us today.
>
>I don't think most transistors drop off in the same way.  Tubes have such 
>low current density (and therefore high Z and low Gm) that, for baseband, 
>electrode capacitance dominates over the fundamental limitations.  Most 
>BJTs have R_L* Ccb dropping off around the same range as fT (which is due 
>to Rb * Cbe and diffusion/recombination).  I suspect that power switching 
>FETs are similarly Ciss * Rg limited; but RF FETs (in Si) have quite high 
>limitations (small Cin and Cout, low Rg), when made properly.
>
>There was one RF part that you found rather lazy, an HBT I think?  That's 
>probably such an example. Relatively high Cout, but fT through the roof?

Lazy? I don't recall that. Phemts and GaN (and, to a lesser extent
SiC) parts have way higher Gm/c ratios than silicon, so make much
better wideband amps.



>
>Coming from your main perspective, I think -- most of your projects have 
>been limited to baseband, and thus your HF limit is pretty much 1 / 
>(2*pi*Cout*R_L).  With peaking, a little over double this, but I'm 
>guessing for your applications, dropping in a superlative GaNFET or 
>whatever is more efficacious and economical.

We do work in time domain. One way to get outrageous gain-bandwidth is
with distributed amplifiers. They are hard to do discretely, so are
generally ICs. You can buy a LF-to-40 GHz amp, for example, from
Hittite or Triquint or whoever they are these days.

>
>And if this were a job job, I'd do the same, but fortunately it's not, so 
>I can take the learning opportunity instead.  :-)  Application, just lab 
>use, maybe a little radio when I get there (hey, just add a wideband 
>antenna and you're set, no need for "tuning the finals" :) ).
>

OK, but RF power amps are usually tuned. That is a lot more practical
(lower cost, fewer stages, higher efficiency) than going wideband.


-- 

John Larkin         Highland Technology, Inc

lunatic fringe electronics 

Am 01.02.2016 um 01:02 schrieb John Larkin:

>>>>>>> I happen to have a complementary pair that's not too slow (2SC2690A and
>>>>>>> 2SA1220A), and I'd like to maximize the bandwidth around that.  The NPN
>>>>>>> side is fine, I have a 30V, 1A, 2GHz transistor that would pair very well
>>>>>>> with it.  Don't have any such thing for the PNP side.
>>>>>>>
>>>>>>> So, what if I fake a PNP, by wrapping, say, a BFT92 around the NPN?
>>>>>>> http://seventransistorlabs.com/Images/Sziklai_Cascode.png
>>>>>>> That'd be Q1 = BFT92, Q2 = 2SC4821, Q3 = 2SA1220A, and resistors for
>>>>>>> flavor, but probably roughly representative.  (Ground wouldn't actually be
>>>>>>> ground-ground, but probably something like +40V, and "+12V" would be
>>>>>>> +45V.)
>>>>>>>
>>>>>>> The combination is still fast... ah, but Sziklai connections have a
>>>>>>> propensity for oscillation all their own, let alone in a cascode, plus
>>>>>>> whatever other machinations I might have for feedback around the thing.
>>>>>>> Game killer?

I must have lost the beginning of this thread on my server, so...

The biggest RF PNP that I have seen is the NXP BFG31, SOT223.
(and I have secured a reel of it :-))

Anything that has a high gain as the product of the gains of two
transistors is unfriendly to feedback since its combined gain
falls at 12 dB/octave and at gain = 1, Mr. Bode will get you.

The modified Darlington with the diode at the base of the second
transistor has a much better behaviour. Beta is only beta1 + beta2,
but it keeps it to much higher frequencies as it falls only with
6 dB. That's much more friendly to feedback.

Maybe one can do the same to the Sziklai?

regards, Gerhard

On Sunday, January 31, 2016 at 3:45:31 PM UTC-8, Clifford Heath wrote:


> What makes you the expert in someone else's moral principles?
> Sheesh, that arrogance surely knows no bounds.

Oh, no, that's wrong.   Morals are about the mores of a society, and
all society members do (must, really) understand those the same way.
All society members become familiar with moral principles, or are cast out.

There's also ethics, which are diverse.   The ethical principles of advertisers and
scientists are vastly different, perhaps not mutually comprehensible.

And there's mathematical principles: those cross over multiple societies
(and would perhaps be comprehended by nonhuman intelligences).

On 01/02/16 11:55, whit3rd wrote:
> On Sunday, January 31, 2016 at 3:45:31 PM UTC-8, Clifford Heath wrote:
>
>
>> What makes you the expert in someone else's moral principles?
>> Sheesh, that arrogance surely knows no bounds.
>
> Oh, no, that's wrong.   Morals are about the mores of a society, and
> all society members do (must, really) understand those the same way.
> All society members become familiar with moral principles, or are cast out.
>
> There's also ethics, which are diverse.   The ethical principles of advertisers and
> scientists are vastly different, perhaps not mutually comprehensible.
>
> And there's mathematical principles: those cross over multiple societies
> (and would perhaps be comprehended by nonhuman intelligences).

I like those distinctions - you draw them well...

but they don't pertain to my criticism of Phil's assumptions about 
bitrex over-achieving on the moral principles Phil ascribes to him.

>> No, it couldn't. �Otherwise nobody would do the right thing when nobody 
>> was looking. �Some people do. 

>No, they don't. Everyone acts in their own selfish interest for their 
>own convenience anyway. 

Well, if that's how it is in your circle, I'm sorry--it must be a very dog-eat dog sort of place.  

But who could, for instance, freely confess to a capital crime, or lay down their life for someone else, if all their motivations were selfish? It's far from unknown, you know. 

Cheers

Phil Hobbs

>> Again, I don't know anybody who advances the view you recite. �Do you? 
>> 

>Sure, they're usually called "evangelicals."

So in other words, you've constructed a caricature but haven't actually discussed it in person with anyone who holds that view. I thought not, because that isn't a view I've encountered except as a straw man. 

Cheers

Phil Hobbs

On 01/02/16 12:13, Phil Hobbs wrote:
>>> No, it couldn't.  Otherwise nobody would do the right thing when nobody
>>> was looking.  Some people do.
>
>> No, they don't. Everyone acts in their own selfish interest for their
>> own convenience anyway.
>
> Well, if that's how it is in your circle, I'm sorry--it must be a very dog-eat dog sort of place.

But you see it's not, not at all. It's just like everywhere else, 
including where religion holds sway... because it's also made of people.

Society has expectations, and life is inconvenient for those who don't 
measure up. That's all. No imagined higher power can improve on that, 
nor does (in fact it just creates a deep division in the mind that too 
often leads to perversion - which is all-too-apparent).

> But who could, for instance, freely confess to a capital crime, or lay down their life for someone else, if all their motivations were selfish? It's far from unknown, you know.

It's all self-expectations. We're social creatures, so we try to live up 
to social expectations... sometimes even where that might mean our own 
death. We've been social creatures for millions of years, but rational 
creatures only for a few tens of thousands - the social factors almost 
always outweigh the rational ones. Absolutist behavior does not, in 
fact, require actual moral absolutes and all the mystical nonsense those 
entail, only imagined ones.

Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> Wrote in message:
> On 01/31/2016 06:24 PM, bitrex wrote:
>> Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> Wrote in
>> message:
>>> On 01/31/2016 04:43 PM, bitrex wrote:
>>>> Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> Wrote in
>>>> message:
>>>>> On 01/31/2016 03:42 PM, bitrex wrote:
>>>>>
>>>>>>>
>>>>>>> You've already said that you're a moral relativist, so
>>>>>>> there's no use appealing to your better nature.  ;)
>>>>>>
>>>>>> True, but it doesn't seem to stop people from trying...
>>>>>
>>>>> A lot of moral relativists are much better than their
>>>>> principles, and I hope you're one.  The principles themselves
>>>>> are so bad that it's scarcely possible for someone to be
>>>>> worse.
>>>>>
>>>>> I try very hard to deal only with straight shooters.  I've had
>>>>> to fire customers who weren't, and I certainly wouldn't
>>>>> knowingly work with someone whose moral ideas were controlled
>>>>> by his own convenience.
>>>>>
>>>>> Cheers
>>>>>
>>>>> Phil Hobbs
>>>>>
>>>>
>>>> The weird thing is, regardless of my moral relativism, I seem to
>>>> generally behave in a moral fashion. But I couldn't tell you
>>>> exactly why. Guess I had those messages drilled into me real good
>>>> and I can't handle the cognitive dissonance. I catch spiders and
>>>> gently put them outside.
>>>
>>> Which does make you better than your principles, at least part of
>>> the time.  You might want to inquire--as a matter of some
>>> urgency--where that higher moral law (for that is what it is) that
>>> judges your intentions comes from.
>>>
>>>>
>>>> But given some of the horrible experiences I've had in life, I
>>>> find it very difficult to believe that morality is anything
>>>> innate or universal. At the end of the day, the Universe doesn't
>>>> care.
>>>
>>> One of the many problems with that view is the immense agreement
>>> between people of all eras and all places on what is and is not OK.
>>> There are disagreements at the edges, e.g. whether you have to be
>>> unselfish towards everybody or just your own
>>> family/tribe/clan/nation, or whether you can have one wife or
>>> five.
>>>
>>> But I claim that you can't actually imagine a society that
>>> sincerely admired people who ran away in battle, or who
>>> double-crossed all their friends, for instance.
>>>
>>
>> Well, yeah, a society made completely of atavistic sociopaths
>> wouldn't last very long.
> 
> I'm not talking about that, I'm talking about the difference between
> "ought to be" and "is".
> 
>> But then that means at some level morality is something that must
>> evolve parallel to humans living in societies at all, which means it
>> must stem from a particular society. i.e. it's not a universal innate
>> quality of humans.
> 
> But that's contrary to the evidence.  You're a victim of your 
> preconceptions.

There's a book I like about what humans are "naturally" like when
 freed from societal pressure.

It's called "Lord of the Flies"

> But how do you define "rotten", if there's no standard?  How can you say 
> that a saint or a great humanitarian is "better" than a Mafia don or a 
> drug dealer, if there's no standard?

These are questions that I struggle with every day. 

> Cheers
> 
> Phil Hobbs
> 
> -- 
> Dr Philip C D Hobbs
> Principal Consultant
> ElectroOptical Innovations LLC
> Optics, Electro-optics, Photonics, Analog Electronics
> 
> 160 North State Road #203
> Briarcliff Manor NY 10510
> 
> hobbs at electrooptical dot net
> http://electrooptical.net
> 


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