Are hybrid parameters useful for design?

practical purposes the ac-current gain and so-called static current gain are identical. This follows because IC in ratio to IB by factor hFE makes deviation in IC, ic, to deviation in IB, ib, that same ratio, of hfe=hFE. This is why the only distinction between hFE and hfe is one of analytical notation, and /also/ why the datasheet specification is so widely used for both. And this has nothing to do with hFE variation with VCE, Early effect, and level of current injection IB.

Thanks, John. That was very gracious of you.

Cheers, JohnS

is because they provide a

I was recently turned down by a VERY BIG semiconductor house when I suggested that, while Spice models can be made as behavioral representations, and thus can't be reverse-engineered, I needed to work with a netlist of the actual chip, so I could find and model all "squirrels". Horrors! Horrors! We can't let you see that! ...Jim Thompson

practical purposes the ac-current gain and so-called static current gain are identical. This follows because IC in ratio to IB by factor hFE makes deviation in IC, ic, to deviation in IB, ib, that same ratio, of hfe=hFE. This is why the only distinction between hFE and hfe is one of analytical notation, and /also/ why the datasheet specification is so widely used for both. And this has nothing to do with hFE variation with VCE, Early effect, and level of current injection IB.

somehow.

If you mean hFE and hfe, they are different. It's rare to see both on a data sheet, but when you do, they are often different.

had

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for practical purposes the ac-current gain and so-called static current ga in are identical. This follows because IC in ratio to IB by factor hFE make s deviation in IC, ic, to deviation in IB, ib, that same ratio, of hfe=hF E. This is why the only distinction between hFE and hfe is one of analytica l notation, and /also/ why the datasheet specification is so widely used fo r both. And this has nothing to do with hFE variation with VCE, Early effec t, and level of current injection IB.

ohn

the

stinct somehow.

Oooh boy, here we go again...different only in definition, but identical nu merically.

practical purposes the ac-current gain and so-called static current gain are identical. This follows because IC in ratio to IB by factor hFE makes deviation in IC, ic, to deviation in IB, ib, that same ratio, of hfe=hFE. This is why the only distinction between hFE and hfe is one of analytical notation, and /also/ why the datasheet specification is so widely used for both. And this has nothing to do with hFE variation with VCE, Early effect, and level of current injection IB.

distinct somehow.

numerically. of course $68,$46,$45 with $68,$66,$65

It's obvious!

Jamie

practical purposes the ac-current gain and so-called static current gain are identical. This follows because IC in ratio to IB by factor hFE makes deviation in IC, ic, to deviation in IB, ib, that same ratio, of hfe=hFE. This is why the only distinction between hFE and hfe is one of analytical notation, and /also/ why the datasheet specification is so widely used for both. And this has nothing to do with hFE variation with VCE, Early effect, and level of current injection IB.

somehow.

They are distinct. If you try building amplifiers that really need to be linear over wide ranges of collector current, the distinction is vital.

One of the major limitations of laser noise canceller performance at low frequency is beta nonlinearity, i.e. 1/h_FE - 1/h_fe.

Cheers

Phil Hobbs

interrogative.

Yo' mama. (How's that for American?) ;0

Cheers

Phil Hobbs

interrogative.

Watch it now, they may become contagious.

Big brother "OBumma" is watching, Can you dig it!

Jamie

practical purposes the ac-current gain and so-called static current gain are identical. This follows because IC in ratio to IB by factor hFE makes deviation in IC, ic, to deviation in IB, ib, that same ratio, of hfe=hFE. This is why the only distinction between hFE and hfe is one of analytical notation, and /also/ why the datasheet specification is so widely used for both. And this has nothing to do with hFE variation with VCE, Early effect, and level of current injection IB.

distinct somehow.

numerically.

No, hFE is a DC measurement (Ic/Ib) and hfe is small-signal, the slope of Ic/Ib at some operating point. They are usually similar, but on data sheets that show both, they are often numerically different.

But since nobody here uses small-signal h-params, it doesn't matter much.

This data sheet actually has hxx params:

Given their span (hre spans an 80:1 range!) they are pretty much useless.

On Mon, 15 Oct 2012 09:16:34 -0700, John Larkin wrote: ...

... I bow in deference ...

Truly, I believe the entrepreneurs and physicists like Phil H, John L, Jim T, Tim W, et al, should consider organising Apprenticeship programs (like in the olden days of Tycho Brahe - Nicholas Copernicus type) so that learners could do hands-on training without filling their minds with unnecessary academic hodge-podge. I say this from an Indian, and a personal, perspective.

I had

rs I

e for practical purposes the ac-current gain and so-called static current g ain are identical. This follows because IC in ratio to IB by factor hFE mak es deviation in IC, ic, to deviation in IB, ib, that same ratio, of hfe=h FE. This is why the only distinction between hFE and hfe is one of analytic al notation, and /also/ why the datasheet specification is so widely used f or both. And this has nothing to do with hFE variation with VCE, Early effe ct, and level of current injection IB.

John

the

istinct somehow.

The key condition to your observation is range of collector currents, usual ly decades. Obviously hFE=hfe for infinitesmal excursions in operating cu rrent. But for large signal, you not only have hFEhfe but significant var iation in each gain with current. That's why they have things like feedback , feedforward, push-pull and a bunch of other techniques.

you

laboratories?

the

While i have used h-paramters for design, it is very uncommon. It can be useful for composing sectional (or block) designs. Not all that useful for designing less than four transistors worth. H-parameters are sort of a co-delopment with the Eberly and Gummel-Poon physics based models (SPICE) to some extent. See if you can find a GE transistor manual 7th edition (best of breed) for a helpful discussion about various early transistor amplifier models.

?-)

. I had

ears I

use for practical purposes the ac-current gain and so-called static current gain are identical. This follows because IC in ratio to IB by factor hFE m akes deviation in IC, ic, to deviation in IB, ib, that same ratio, of hfe =hFE. This is why the only distinction between hFE and hfe is one of anal ytical notation, and /also/ why the datasheet specification is so widely us ed for both. And this has nothing to do with hFE variation with VCE, Early effect, and level of current injection IB.

n John

in the

distinct somehow.

numerically.

I don't need you reading me EE 101 on the subject. The hFE is usually a min

-max range with guardbanding and, hopefully a 'typical' hFE variation with IC,Q. The hfe whenever presented are usually typical, at fixed IC,Q and VEC ,Q and freq, and should be larger than hFE at Q-point because it doesn't ha ve to contend with that small cut-in region where hFE trends to 0.

Dunno how you even select a transistor for a non-trivial app without at lea st mentally computing a hybrid-pi. The BE diffusion capacitance can be a bi ggie with finite source impedance drive, and, God forbid, you might even us e Miller's Rule here and there to do a quick estimate of bandwidth and rise times.

The h-parameter models combine trivially for series-shunt feedback configurations.

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Hmmm. Perhaps a lot of "behavioral models" come from sloppily executed h-parameter versions of ICs.

?-)

Naaaah! They come from companies that have marketing managers in charge of modeling. Names upon request ;-) ...Jim Thompson

tradition

better

country

paradigm of meritocracy and not its absence. Meritocracy is a political term which describes the selection process for administration positions as being based on standardized test screening, aka civil service examinations, versus personal and/or political party affiliation.

Except that it all too easily becomes minimockracy. Which civil service does become in all nations.

?-)

non-governmental professions. How damned dumb are you? Here's a brief overview even you should be able to understand, unless you question the authority of OPM:

Question their "authority", certainly; challenging govmonk authority is a treasured US national pastime. I even more so question their capability to execute such.

?-)

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It

_really_

If you SPICE too soon you probably already missed something important. I'll bet that most of us agree that "feel" for circuits is gained from lots of working with real circuits rather than from any amount of theory.

?-)