FET transfer function - best and worst cases

P

Paul Burridge

Guest
Hi all,

Say a datasheet lists values of

Idss= 20mA - 60mA
Vp= 2V - 6V

(pulling plausible figures out of the air)

Typical values rarely seem to be listed for FETs, so I assume there's
a fairly even distribution of real-world manufacturing variations
between the two extremes.

Now the question is, one would expect the FET with the Idss of 20mA to
have a Vp of 2V in the above example, and one with an Idss of 60mA to
have a Vp of 6V, thereby preserving the characteristic shape of the
curve across the whole range of possible values. But is it possible to
get the occasional rogue real-world FET that has a Vp of 2V and an
Idss of 60mA or one with a Vp of 6V that gives an Idss of 20mA,
thereby with totally different characteristic curves?

Thanks,

p.
--

"What is now proved was once only imagin'd." - William Blake, 1793.
 
On Fri, 10 Sep 2004 17:20:53 GMT, "Kevin Aylward"
<salesEXTRACT@anasoft.co.uk> wrote:

More or less, yes, but the curves still all use the same basic equation.
Vt and beta (transconducance parameter) are essentially independent, so
you can have any K.W/L with any Vp.
Did you get my e-mail, Kev?
--

"What is now proved was once only imagin'd." - William Blake, 1793.
 
Paul Burridge wrote:
On Fri, 10 Sep 2004 17:20:53 GMT, "Kevin Aylward"
salesEXTRACT@anasoft.co.uk> wrote:

More or less, yes, but the curves still all use the same basic
equation. Vt and beta (transconducance parameter) are essentially
independent, so you can have any K.W/L with any Vp.

Did you get my e-mail, Kev?
Aparantly not.

Did you remove EXTRACT. The other one is kevin.aylward with the obvious
addition.

Kevin Aylward
salesEXTRACT@anasoft.co.uk
http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.
 
On Fri, 10 Sep 2004 19:20:20 GMT, "Kevin Aylward"
<salesEXTRACT@anasoft.co.uk> wrote:

Paul Burridge wrote:
On Fri, 10 Sep 2004 17:20:53 GMT, "Kevin Aylward"
salesEXTRACT@anasoft.co.uk> wrote:

More or less, yes, but the curves still all use the same basic
equation. Vt and beta (transconducance parameter) are essentially
independent, so you can have any K.W/L with any Vp.

Did you get my e-mail, Kev?

Aparantly not.

Did you remove EXTRACT. The other one is kevin.aylward with the obvious
addition.
I assume you own the domain in question? Ergo, any old string before
the @ should get through. Ah! I see. I take that back. I'll resend it
now with the appropriate bit removed.
--

"What is now proved was once only imagin'd." - William Blake, 1793.
 
Paul Burridge wrote:
On Fri, 10 Sep 2004 19:20:20 GMT, "Kevin Aylward"
salesEXTRACT@anasoft.co.uk> wrote:

Paul Burridge wrote:
On Fri, 10 Sep 2004 17:20:53 GMT, "Kevin Aylward"
salesEXTRACT@anasoft.co.uk> wrote:

More or less, yes, but the curves still all use the same basic
equation. Vt and beta (transconducance parameter) are essentially
independent, so you can have any K.W/L with any Vp.

Did you get my e-mail, Kev?

Aparantly not.

Did you remove EXTRACT. The other one is kevin.aylward with the
obvious addition.

I assume you own the domain in question? Ergo, any old string before
the @ should get through.
No. I set it up to bounce back if not exactly correct. Two much spam
otherwise.

Ah! I see. I take that back. I'll resend it
now with the appropriate bit removed.
And working on the new bug you discovered!

Kevin Aylward
salesEXTRACT@anasoft.co.uk
http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.
 
I read in sci.electronics.design that John Larkin <jjlarkin@highlandSNIP
techTHISnologyPLEASE.com> wrote (in <ak96k0d9a1uchf14vontulbnudsoo05pp6@
4ax.com>) about 'FET transfer function - best and worst cases', on Sat,
11 Sep 2004:
just renamed to Eudyna, whatever that means
Greek, 'good force'.
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk
 
On Sat, 11 Sep 2004 20:45:30 +0100, John Woodgate
<jmw@jmwa.demon.contraspam.yuk> wrote:

I read in sci.electronics.design that John Larkin <jjlarkin@highlandSNIP
techTHISnologyPLEASE.com> wrote (in <ak96k0d9a1uchf14vontulbnudsoo05pp6@
4ax.com>) about 'FET transfer function - best and worst cases', on Sat,
11 Sep 2004:
just renamed to Eudyna, whatever that means

Greek, 'good force'.

My favorite Taiwanese company name is "Mean Well Electronics."

John
 
On Sat, 11 Sep 2004 14:53:24 -0700, John Larkin
<jjlarkin@highlandSNIPtechTHISnologyPLEASE.com> wrote:

On Sat, 11 Sep 2004 20:45:30 +0100, John Woodgate
jmw@jmwa.demon.contraspam.yuk> wrote:

I read in sci.electronics.design that John Larkin <jjlarkin@highlandSNIP
techTHISnologyPLEASE.com> wrote (in <ak96k0d9a1uchf14vontulbnudsoo05pp6@
4ax.com>) about 'FET transfer function - best and worst cases', on Sat,
11 Sep 2004:
just renamed to Eudyna, whatever that means

Greek, 'good force'.


My favorite Taiwanese company name is "Mean Well Electronics."
Muslims reckon that if you wipe your arse with the right hand, it's
unlucky.
--

"What is now proved was once only imagin'd." - William Blake, 1793.
 
In article <nl07k0l06347ig1p6e530cplsrumf3olqe@4ax.com>,
Paul Burridge <pb@notthisbit.osiris1.co.uk> wrote:

Muslims reckon that if you wipe your arse with the right hand,
it's unlucky.
Like a number of (apparently) religious strictures,
it has a basis of practicality. In any country with
little water it is not always practical to wash
properly. So you wipe your arse with your left
hand, and make damned sure you only use your right
hand to eat with.

Get things mixed up, and you are almost guaranteed
to be 'unlucky'.

--
Tony Williams.
 
In article <kju8k0d651a41mk8l6aahsj9ecuu4mn73s@4ax.com>,
Spehro Pefhany <speffSNIP@interlogDOTyou.knowwhat> wrote:

Which is why removing the right hand surgically is a ticket to
being shunned for life. Nobody wants some dude fishing around in
the communal food bowl with his wiping hand.
Blimey! Never thought of that.......

--
Tony Williams.
 

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