How to determine Zin, Yout for RF transistor, from A parameters

"whit3rd" <whit3rd@gmail.com> wrote in message 
news:5b517bac-a874-4cbc-95e0-5b9923f52d39@googlegroups.com...
> Hey, I still use slide rules!  Best way to set up a resistor ratio
> while rummaging through the stock drawers for a suitable pair
> to build the divider.

There are better ways for that, now, too:
http://jansson.us/resistors.html
http://kirr.homeunix.org/electronics/resistor-network-finder/
(and other links on the About page)

Tim

-- 
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Contract Design
Website: http://seventransistorlabs.com 

On Mon, 8 May 2017 16:30:31 -0500, "Tim Williams"
<tiwill@seventransistorlabs.com> wrote:

>"whit3rd" <whit3rd@gmail.com> wrote in message 
>news:5b517bac-a874-4cbc-95e0-5b9923f52d39@googlegroups.com...
>> Hey, I still use slide rules!  Best way to set up a resistor ratio
>> while rummaging through the stock drawers for a suitable pair
>> to build the divider.
>
>There are better ways for that, now, too:
>http://jansson.us/resistors.html
>http://kirr.homeunix.org/electronics/resistor-network-finder/
>(and other links on the About page)
>

Excel.  ;-)

On Mon, 8 May 2017 20:42:49 +0100, "Kevin Aylward"
<kevinRemovAT@kevinaylward.co.uk> wrote:

>>wrote in message news:tp61hcdr752v3ammue1gdfcp5e2ckv3mk6@4ax.com...
>
>>On Sun, 7 May 2017 19:49:42 -0700 (PDT), tabbypurr@gmail.com wrote:
>
>>>On Monday, 8 May 2017 01:52:15 UTC+1, k...@notreal.com  wrote:
>>
>>>> Halfa megabuck is nothing.
>>
>>>not in my universe
>
>>Well, I'll be buying damned few mask sets myself but a half-a-magabuck
>>isn't a lot of money when talking about ASIC or custom chip
>>development.  Gate arrays may be significantly less, of course.
>
>It depends on what you are doing.

Sure.  If you aren't doing cutting edge stuff you don't pay cutting
edge prices.  That's a surprise?
>
>0.18u BiCmos is great for a whole bunch of stuff. Maybe $50k -$100k for an 
>engineering prototype build.

Gate array, perhaps.  All the expensive masks are common.  All you're
doing is buying metal.

>22nm, another story in cost. High precison analog usually means gates > 1u. 
>Low noise means > 10u, anyway so...
>
>-- Kevin Aylward
>http://www.anasoft.co.uk - SuperSpice
>http://www.kevinaylward.co.uk/ee/index.html 

On Mon, 8 May 2017 16:30:31 -0500, "Tim Williams"
<tiwill@seventransistorlabs.com> wrote:

>"whit3rd" <whit3rd@gmail.com> wrote in message 
>news:5b517bac-a874-4cbc-95e0-5b9923f52d39@googlegroups.com...
>> Hey, I still use slide rules!  Best way to set up a resistor ratio
>> while rummaging through the stock drawers for a suitable pair
>> to build the divider.
>
>There are better ways for that, now, too:
>http://jansson.us/resistors.html
>http://kirr.homeunix.org/electronics/resistor-network-finder/
>(and other links on the About page)
>
>Tim

This program

https://www.dropbox.com/s/ajmp4kbio1uf7qn/Rugrat.jpg?dl=0

finds ratios based on the resistors that we have in stock.



-- 

John Larkin         Highland Technology, Inc
picosecond timing   precision measurement 

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

<krw@notreal.com> wrote in message 
news:0ir1hc9u0geib5titupvcfg9a10qvfadqi@4ax.com...
> Sure.  If you aren't doing cutting edge stuff you don't pay cutting
> edge prices.  That's a surprise?

Yes, actually.

What I don't get:

How come all that old iron from the 60s and 70s, with big fat huge micron 
linewidths, isn't in peoples' garages?  It just went straight to the scrap 
yard.  (Except for the very few legacy lines that are making stuff like 741s 
and LM13700s.)

Another perspective:
PCBs are hobbyist/maker friendly.  Get a dozen little boards for about as 
many bucks.

Cheap PCBs have shitty specs, but they usually still meet IPC minimums (7/7 
mils), and that's good enough for most SMT, and more than enough for any 
THT.

You can get much finer spec PCBs, just as easily -- if more expensive.  The 
scaling of that expense seems to be maybe quadratic (3 times finer pitch --> 
10 times cost), still depending on quantity of course.

But it's not like it's going to break your whole business model if you're 
building a device in your garage.

As soon as you put stuff on a wafer, it's suddenly a big deal, say with 
COMSIS and all that.  Big fab stuff.  Big bucks.  Big lead times.  Where's 
the guy with the garage fab spinning protos in a couple days?

Tim

-- 
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Contract Design
Website: http://seventransistorlabs.com 

On Mon, 8 May 2017 19:16:04 -0500, "Tim Williams"
<tiwill@seventransistorlabs.com> wrote:

><krw@notreal.com> wrote in message 
>news:0ir1hc9u0geib5titupvcfg9a10qvfadqi@4ax.com...
>> Sure.  If you aren't doing cutting edge stuff you don't pay cutting
>> edge prices.  That's a surprise?
>
>Yes, actually.
>
>What I don't get:
>
>How come all that old iron from the 60s and 70s, with big fat huge micron 
>linewidths, isn't in peoples' garages?  It just went straight to the scrap 
>yard.  (Except for the very few legacy lines that are making stuff like 741s 
>and LM13700s.)

Because it cost more to run than it was worth.

>Another perspective:
>PCBs are hobbyist/maker friendly.  Get a dozen little boards for about as 
>many bucks.
>
>Cheap PCBs have shitty specs, but they usually still meet IPC minimums (7/7 
>mils), and that's good enough for most SMT, and more than enough for any 
>THT.
>
>You can get much finer spec PCBs, just as easily -- if more expensive.  The 
>scaling of that expense seems to be maybe quadratic (3 times finer pitch --> 
>10 times cost), still depending on quantity of course.

That's surprising?  If it's not needed for every application, it'll
have a smaller market.  Smaller market => more expensive.  Rinse.
Repeat.

>But it's not like it's going to break your whole business model if you're 
>building a device in your garage.

You couldn't afford the infrastructure, if you could afford the tools.

>As soon as you put stuff on a wafer, it's suddenly a big deal, say with 
>COMSIS and all that.  Big fab stuff.  Big bucks.  Big lead times.  Where's 
>the guy with the garage fab spinning protos in a couple days?

On Monday, May 8, 2017 at 10:43:55 AM UTC-4, Jeroen Belleman wrote:
> On 2017-05-08 15:14, Okkim.Atnarivik@invalid.fi wrote:
> > On Monday, May 8, 2017 at 10:43:22 AM UTC+3, Jeroen Belleman wrote:
> >> On 2017-05-06 05:50, dakupoto@gmail.com wrote:
> >>> Could some RGF/microwave guru on this newsgroup
> >>> please help ? I am looking at the datasheet for
> >>> a ONSemi RF transistor, with the S parameters
> >>> listed for various frequencies. What would be
> >>> a quick and easy(that I can code as a simple
> >>> C program) way to convert these to the
> >>> corresponding Zin and Yout. Thanks in
> >>> advance for your hints/suggestions.
> >>>
> >>
> >> Since no one took the trouble to simply reply to your
> >> question, here we go.
> >>
> >> The S11 parameter is the input reflection coefficient.
> >> It's just a different way to represent input impedance.
> >> S11 is in fact what you would measure across the
> >> arms of a Wheatstone bridge with the relevant impedance
> >> in one of the arms and Z0 = 50 Ohm resistors in all the
> >> others. Converting, Zin = Z0*(1+S11)/(1-S11).
> >>
> >> The same conversion applies to S22 and Zout. Yout=1/Zout.
> >>
> >> Bear in mind that these are linearized parameters of
> >> a basically non-linear device at specific bias conditions
> >> and with a specific excitation level.
> >>
> >> All complex number math, naturally.
> >>
> >> Jeroen Belleman
> >
> >    For an unilateral transistor i.e. S12 nonzero, the formulae are
> > a bit more complicated:
> >
> > Zin = Z0 * ((1+S11)*(1-S22)+S12*S21) / ((1-S11)*(1-S22)-S12*S21)
> > Yout = 1/Z0 * ((1+S11)*(1-S22)+S12*S21) / ((1+S11)*(1+S22)-S12*S21)
> >
> >    One obtains those from signal graph analysis, or (as I did) by
> > copying from Pozar's book.
> >
> >    Regards,
> >             Mikko
> >
> 
> I didn't try to verify in detail, but it looks like there's a
> error in there, because those expressions do not reduce to mine
> if one sets S12=0.
I only starred at it a bit, but it looks to work,  
(a factor of  1-S22 cancels top and bottom.) 
(I know little of S-parameters)

George H. 
> 
> Jeroen Belleman

On Tuesday, May 9, 2017 at 4:41:35 AM UTC+3, George Herold wrote:
> On Monday, May 8, 2017 at 10:43:55 AM UTC-4, Jeroen Belleman wrote:
> > On 2017-05-08 15:14, Okkim.Atnarivik@invalid.fi wrote:
> > > On Monday, May 8, 2017 at 10:43:22 AM UTC+3, Jeroen Belleman wrote:
> > >> On 2017-05-06 05:50, dakupoto@gmail.com wrote:
> > >>> Could some RGF/microwave guru on this newsgroup
> > >>> please help ? I am looking at the datasheet for
> > >>> a ONSemi RF transistor, with the S parameters
> > >>> listed for various frequencies. What would be
> > >>> a quick and easy(that I can code as a simple
> > >>> C program) way to convert these to the
> > >>> corresponding Zin and Yout. Thanks in
> > >>> advance for your hints/suggestions.
> > >>>
> > >>
> > >> Since no one took the trouble to simply reply to your
> > >> question, here we go.
> > >>
> > >> The S11 parameter is the input reflection coefficient.
> > >> It's just a different way to represent input impedance.
> > >> S11 is in fact what you would measure across the
> > >> arms of a Wheatstone bridge with the relevant impedance
> > >> in one of the arms and Z0 = 50 Ohm resistors in all the
> > >> others. Converting, Zin = Z0*(1+S11)/(1-S11).
> > >>
> > >> The same conversion applies to S22 and Zout. Yout=1/Zout.
> > >>
> > >> Bear in mind that these are linearized parameters of
> > >> a basically non-linear device at specific bias conditions
> > >> and with a specific excitation level.
> > >>
> > >> All complex number math, naturally.
> > >>
> > >> Jeroen Belleman
> > >
> > >    For an unilateral transistor i.e. S12 nonzero, the formulae are
> > > a bit more complicated:
> > >
> > > Zin = Z0 * ((1+S11)*(1-S22)+S12*S21) / ((1-S11)*(1-S22)-S12*S21)
> > > Yout = 1/Z0 * ((1+S11)*(1-S22)+S12*S21) / ((1+S11)*(1+S22)-S12*S21)
> > >
> > >    One obtains those from signal graph analysis, or (as I did) by
> > > copying from Pozar's book.
> > >
> > >    Regards,
> > >             Mikko
> > >
> > 
> > I didn't try to verify in detail, but it looks like there's a
> > error in there, because those expressions do not reduce to mine
> > if one sets S12=0.
> I only starred at it a bit, but it looks to work,  
> (a factor of  1-S22 cancels top and bottom.) 
> (I know little of S-parameters)
> 
> George H. 
> > 
> > Jeroen Belleman

I only checked the S12=0 case in my head while typing,
but I also think it simplifies correctly. Btw, S12 not 
equal to zero should be called the NON-unilateral case. 

Actual calculation with S-parameters is messy because they are
complex-valued, that's why I like my Casio fx-991ES. Simple,
non-graphing, but can do complex arithmetic both in x+iy and in
the angular format on the fly (manufacturers usually give 
S-params in angular).

The simple reason for the more complicated formulae is that S12<>0
implies feedback, and in this case the output termination
affects the input impedance and vice versa. Like, if you change 
the output loading from 50 ohms (the S-param case) into a short 
(the Y-param case).

Regards,
          Mikko

On 2017-05-09 03:41, George Herold wrote:
> On Monday, May 8, 2017 at 10:43:55 AM UTC-4, Jeroen Belleman wrote:
>> On 2017-05-08 15:14, Okkim.Atnarivik@invalid.fi wrote:
[Snip!]
>>>
>>>     For an unilateral transistor i.e. S12 nonzero, the formulae are
>>> a bit more complicated:
>>>
>>> Zin = Z0 * ((1+S11)*(1-S22)+S12*S21) / ((1-S11)*(1-S22)-S12*S21)
>>> Yout = 1/Z0 * ((1+S11)*(1-S22)+S12*S21) / ((1+S11)*(1+S22)-S12*S21)
>>>
>>>     One obtains those from signal graph analysis, or (as I did) by
>>> copying from Pozar's book.
>>>
>>>     Regards,
>>>              Mikko
>>>
>>
>> I didn't try to verify in detail, but it looks like there's a
>> error in there, because those expressions do not reduce to mine
>> if one sets S12=0.
> I only starred at it a bit, but it looks to work,
> (a factor of  1-S22 cancels top and bottom.)

Indeed, I stand corrected.

Jeroen Belleman

On a sunny day (Mon, 8 May 2017 21:15:52 +0100) it happened "Kevin Aylward"
<kevinRemovAT@kevinaylward.co.uk> wrote in
<i96dnaqjedtkTI3EnZ2dnUU7-VPNnZ2d@giganews.com>:

>wrote in message news:10gvgcdc7nt8r70tcdn5iibeepqfoor1c7@4ax.com...
>
>On Sun, 7 May 2017 20:52:06 +0100, "Kevin Aylward"
><kevinRemovAT@kevinaylward.co.uk> wrote:
>
>>"Jan Panteltje"  wrote in message news:oekvo1$jak$1@news.datemas.de...
>>
>>On a sunny day (Sat, 6 May 2017 11:24:14 -0500) it happened "Tim Williams"
>
>
>>There is a big difference between chip and board level design.
>
>My basic point through all of this was to dismiss this general idea of 
>"spice isn't about the real world.... isn't good enough etc...etc..."
>
>Pretty much every modern product today, exists because of the ics in them. 
>All ic design is done in the virtual world. Only a tiny minority of ic 
>designs have any dependence on unknown board level issues.
>
>Sure, I am not an RF specialist.  However, I have done a few bits and bobs 
>at the several GHz region. I have also spoken to RF specialists. Most have 
>missed the boat. They think in ways passed on from their fore fathers, that 
>were passed down from their forefathers.
>
>The days of graphical techniques and manual equation solving are gone. 
>Whether its electronics, designing the same bloody energy efficient car body 
>shape, trading stocks and shares, its all done by running millions of 
>simulations. It what TFlop computers are very good at. You just need to 
>learn how to drive them correctly. Unfortunatly, as far a board level spice 
>users go, most don't know how.

It think there is something very bad about that trend,
and in fact I think it is not really happening that way.
You are right about all those sims being used.

I have proposed, in a more politically oriented forum, the
'mama app'
It is meant for CEOs' and higher, like presidents, the user interface is simple:
mama I want <whatever>

The rest is done by software that steers little robots.
No education or experience is needed, you only need to learn how to say 'mama I want'

Then for the future of humanity and stability, well I have some ideas.
History has shown we had to start from scratch after those highly developed civilizations collapsed
Technology then got better.

Problem with mathematicians is that they tend to take formulas that are an approximation of reality
and build their own universe on that.
Mathematicians are OK to solve and build models from experimental data.
But they need the reality check.
Only in very rare cases does it work the other way around.
we are, physical beings in a physical world, mathematics is just a subset in the neural net.