bipolar (BJT) transistor families for audio power output stages

syn08, you miss the fact that Ft are measured with very low impedance
sources, thus rendering the influence of Cbe irrelevant for a large
part of the curve..

No. A rigurous definition of Fc is "the frequency at which the current through the imaginary and real part of the input impedance are equal".

Otherwise, I don't know where the posted curves are, therefore I can't really get into such a discussion.
 
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Joined 2006
OK guys, someone would like to bring and post a measured comparison of OP stages based on 2SA1943/2SC5200, MJL1302/3281 and MJL21194/3 under heavy load conditions at some 30kHz? This might be very ineteresting, probably more than a purely theoretical debate.

Whoever does these comparisons please use the latest japanese versions and not 30 year old parts, the new parts for audio outputs by toshiba is 2sa2121 and 2sc5949. These have according to datasheet about the same SOA of the onsemi and are faster than the older parts they replace with much lower the capacitances of the onsemi.
Some comparisons with sankens like 2sa1303 and compl would also be welcome.

Bob, these are some of the more modern japanese transistors you asked about. Other outputs Ive tried is allegro sytems 2sc6011 and compl which perform very well too. From what i understand these are made in the US using sanken process technology.
 
I am very sure that BV is very well aware of this, and can solve it on a circuit basis very effectively.

We are not in a 1st class of a primary school here.

PMA,

It may very well be the case that BV understands this. It may also be that this issue is primary school for some as smart as you.

However, I always try to post clearly and completely so that most people reading the forum can understand and learn something if they do not know it already. I always try to do this in a way that is not condescending.

Cheers,
Bob
 
here the configuration...
if the 2R resistance is increased, Ft collapse dramatically..
each current source is adjusted so the Ic is 4 A...

Where did you get that circuit for measuring ft? It does not look like it measures ft to me. Looks like it is measuring some combination of gm and Miller effect from the Ccb capacitor. If you claim this is a legit circuit for measuring ft, please give us a reference for where you got it.

Thanks,
Bob
 
Where did you get that circuit for measuring ft? It does not look like it measures ft to me. Looks like it is measuring some combination of gm and Miller effect from the Ccb capacitor. If you claim this is a legit circuit for measuring ft, please give us a reference for where you got it.

Thanks,
Bob

sorry, bob, i didn t mention the actual testbed...
the ac source is not at fixed frequency...
there a sweep in the programed frequency range, and the soft calculate
the frequency response in the boundaries you choose...


regards
 
Disabled Account
Joined 2008
I believe that the Linear Systems LSK389 is a copy of the famous National NPD5564 that was available beginning in the 1970's.

BTW, beware that just because someone uses some of the same numbers does not mean the transistor is a copy or even has the same specs.

Interesting, maybe Roadbagger has some more info?

BTW: I tried to order some samples from Linear Systems
:snail::wchair::dead:
 
I still can't open the files. Can you use some more accessible image format?

i m sorry, i tried, but the converted image appear black, with no reference
of the components..
i dont understand, as the emf format is a windows one that date back to
windows95...it s simply opened with windows telecopy image displayer which is
native on every windows, since w95...
 
No. A rigurous definition of Fc is "the frequency at which the current through the imaginary and real part of the input impedance are equal".
.

you dont stick to the issue...
we are talking about absolute values in actual devices..
if you prefer, let s say that the frequency at which real and imaginary parts
are equal are (!) higher in the toshiba devices than in the onsemi s, according
to simulations made using models delivered by the respective manufacturers...

does this kind of formulation suits you?...........
 
Whoever does these comparisons please use the latest japanese versions and not 30 year old parts, the new parts for audio outputs by toshiba is 2sa2121 and 2sc5949. These have according to datasheet about the same SOA of the onsemi and are faster than the older parts they replace with much lower the capacitances of the onsemi.
Some comparisons with sankens like 2sa1303 and compl would also be welcome.

Bob, these are some of the more modern japanese transistors you asked about. Other outputs Ive tried is allegro sytems 2sc6011 and compl which perform very well too. From what i understand these are made in the US using sanken process technology.

I think you need to look at the datasheets. The 2SC5949 is a bit of a dog compared to the OnSemi MJL. Its ft is down to 9 MHz at only 4A. At least they show an ft vs. Ic curve. Cob is about the same as the MJL's 260 pF. SOA of the 2SC5949 is only 800 mA at 100V, no better than the MJL. I do not understand how you can assert that this is a better transistor than the MJL based on the datasheet.

I didn't look hard at it, but its beta vs. Ic linearity also looks a bit inferior to the MJL.

Toshiba's 30 year old transistors looked better.

Cheers,
Bob
 
sorry, bob, i didn t mention the actual testbed...
the ac source is not at fixed frequency...
there a sweep in the programed frequency range, and the soft calculate
the frequency response in the boundaries you choose...


regards

Hi Wahab,

I don't think that answers the question. I know you were sweeping the frequency. Where did you get the idea that the circuit is appropriate for measuring ft? Do you have a reference? Your circuit does not appear to measure AC beta vs. frequency, so I do not believe it is useful for evaluating ft.

Cheers,
Bob
 
you dont stick to the issue...
we are talking about absolute values in actual devices..
if you prefer, let s say that the frequency at which real and imaginary parts
are equal are (!) higher in the toshiba devices than in the onsemi s, according
to simulations made using models delivered by the respective manufacturers...

does this kind of formulation suits you?...........

No. First, you are comparing simulation models not actual devices, some models are notoriously bad or simply do not have provisions for the Beta(f) dependency. Secondly, you need to explain how you simulated those dependencies.
 
Disabled Account
Joined 2006
The devices you mention here should be compared to the OnSemi NJW (TO-3P) devices and not the MJL (TO-264) devices.

Why in the world would you want to compare to a transistor with a higher SOA package, the toshibas are TO264. For TO3p youll have to look at the sanken range and here youll see even a larger advantage for the japanese devices.


Bob nowhere does onsemi accurately state what the capacitance is, so one wont know for sure but ill only believe it if I test it myself and see it.
 
No. First, you are comparing simulation models not actual devices, some models are notoriously bad or simply do not have provisions for the Beta(f) dependency. Secondly, you need to explain how you simulated those dependencies.

so you trust onsemi s datasheets, but not the models they publicly
deliver?..seems bad faith to me..

what is measured by the circuit is the ac voltage gain with a constant
transconductance..
if you prefer, fixed transconductance and variable frequency...

the datasheets show variable transconductance and fixed freaquency,
exactly the contrary....

this is misleading, as the current gain frequency product become
less and less relevant with increasing frequency...
The point is that MJL3281 and 2SC5200 have the same Ft on the datasheets
(you trust datasheets, you said) at 30mhz typical for toshiba, and minimum for on semi..
2SA1302 , the antedeluvian device is credited a meager 10 mhz , but as minimum guaranted..

now, in common emmiter mode, with constant current AC source and low
impedance load on the collector, in the aim to reduce to very little
the influence of the parasistic capacitors, i.e , Cbe and Cbc , the toshiba devices show better bandwith performances , which
tell that beta(f) deacrease sooner on the onsemi s device..

have you an explanation other than the easy one that is to blame the
models wich i said it ad nauseam are those of the manufacturers...