OT: United States of Feeding Tubes

Jim Thompson · Mar 26, 2005

On 26 Mar 2005 09:38:32 -0800, Winfield Hill
<hill_a@t_rowland-dotties-harvard-dot.s-edu> wrote:

Jim Thompson wrote...
Jim Thompson wrote:

[snip]
I was looking thru "pwrmos.lib" in the new OrCAD/PSpice release...
everything is STILL Level=3.
So I think the problem is the manufacturers don't care about
spending money on quality modeling.

It's literally been just shy of 20 years since I designed anything
with a power-FET, and _most_ of my I/C foundry CMOS models do seem to
work subthreshold (for small-signal analog).

Win, WHAT is important to you in power-FET modeling, subthreshold?

Maybe we can mutually determine the "fix" for the models?

OK, here's what I wrote early in the discussion, last December 31st,

Well, then surely you'll want viable Spice MOSFET models, because
you'll be using the FETs throughout their useful linear range, and
the output-stage crossover region is critical.

Sadly most standard Spice library VMOS models simply don't do the
subthreshold linear region. For example, see the 10-decade plots
on page 123 of our book. A jellybean 2n7000 is rather similar to
the VN01 that we show in figure 3.14, and certainly a proper Spice
model should be able to make that plot. But I'd be surprised if
your standard Spice libraries work properly below say 5 to 20mA,
which is not that far below the FET's maximum current. Keep in
mind that linear power FET circuitry always operates well below
the maximum rated FET switching current, to keep power dissipation
junction heating under control.

I since confirmed this with some 2n7000 Spice-model testing...
the SQRT-Id plot goes to zero at 2.4V (wrong answer), an abrupt
transition occurs at 9mA (wrong), and another at 2mA (gross), to
a 5-decade subthreshold exponential transconductance (correct) at
Vgs = 2.4V (wrong). Rather useless for linear-circuit modeling.

The bottom line is you'll have to start your FET-amplifier design
exercise by designing some decent FET models. Let us know what you
come up with.

With respect to the Id-vs-Vgs curves on page 123 of our book, and
the g_m plots on page 132, the spice models should be able to show
this performance. At subthreshold currents a FET acts very much
like a transistor with respect to transconductance, etc., and when
a power FET is used in linear audio amplifiers, e.g. in class AB,
it may go through this region during each cycle. So in using Spice
to determine distortion and evaluate various design configurations,
surely it's necessary for the FET model to smoothly simulate the
subthreshold region, and properly progress to the current-saturated
regions that are normally accurately modeled. I'm going to go in
to the lab and take some detailed 2n7000 measurements later today.

I'm game. I just love this kind of puzzle... fit a nasty model to
nasty data ;-)

Back in the infancy of simulators I DID roll my own(*) BJT models from
lab data.

(*) With the assistance of oldest son, who was already studying
programming at U of A.

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice

480)460-2350 | |
| E-mail Address at Website Fax

xray · Mar 27, 2005

On Fri, 25 Mar 2005 09:10:54 -0700, Jim Thompson
<thegreatone@example.com> wrote:

Jim won't read this because he blocked me, but I used to like him when
this was his main sort of communication in the group. I respect that.
Good stuff for everyone who is paying attention.

I do still hate him for his well publicised politics though.

My well "publicised" politics represent the type of personality that
beat the Brits, in the Revolution, against _insurmountable_ odds.

I'm sorry you hate me, so please expire promptly, choking on your bile
;-)

I guess I fell out of blockage since you replied directly to my message.

Sorry I am delayed in replying but haven't been monitoring here for a
bit.

So, I am not sure if I hate you. John pointed out that our opinions on
this stuff are not absolute and so forth.

I do strongly disagree with your opinions on certain recent things,
though. Well for instance, "My well "publicised" politics represent the
type of personality that beat the Brits, in the Revolution, against
_insurmountable_ odds."

Ok, but that is a bit dated. Since then, I think we used the same sort
of politics during Vietnam and it didn't play out well in the overall
scheme of US sucesses. You can tell me how it differs, but it smells the
same to me, and I was walking around there (Vietnam), losing comarades
and ultimately our county lost the ill-advised war.

This particular one (Iraq) is looking more positive lately than I
expected, but it is far from played out in the grand scheme of things. I
actually believe our real intentions were mostly honorable. I dearly
hope it turns out positive in the long run. We shall see.

One can take a point of view that the whole intention of our intrusion
into the center of a middle east region that happens to hold the
majority of the world's currently known oil supplies is only altruistic,
but you are a fool if you think the rest of the world would easily agree
with that.

Now, let us remember that the whole stated pretense for a reason to make
a preemtive strike on this contry turned out to be WMD's that ultimately
did not exist.

In the mean time, your talking trash against various parts of Europe
only helps to add to our ugly American image.

So you talk trash against our European allies, you supported a war that
was initated based on lies.

Based on that I think you are a defacto idiot politically (maybe you are
intelligent otherwise).

So, I acknowledge that you are not an idiot. You are actually very
intelligent. Just shut up on the stuff that is not your realm of
expertise.

John Woodgate · Mar 27, 2005

I read in sci.electronics.design that xray <notreally@hotmail.invalid>
wrote (in <4c1d41pd3sa35r8bkun5vavf0t6qaa3u90@4ax.com&gt

about '2n7000
spice models', on Sun, 27 Mar 2005:

In the mean time, your talking trash against various parts of Europe
only helps to add to our ugly American image.

Well, he gets attacked by European socialists, but I agree that his
retaliation is a bit puerile, just like parliamentary exchanges of
compliments.

So you talk trash against our European allies, you supported a war that
was initated based on lies.

There's no point in opposing it now. It's done, and we have to bear the
consequences - getting Iraq back on its feet will be a LONG job.

Based on that I think you are a defacto idiot politically (maybe you
are intelligent otherwise).

Think about politicians (even in high office) for a bit. Do they not all
show signs of idiocy? Especially in terms of misbehaving in their
private lives and fondly expecting not to be found out? But not only
that; here in UK we are warming up for an election and what does the
(now 'former'!) Deputy Chairman of the Conservative Party do? Stands up
at a dinner and effectively says 'We are lying to the nation about our
plans for public spending cuts.' Can you imagine anything much more
stupid?

On this basis, Jim, as a 'de facto idiot politically' clearly qualifies
for President! (;-)
--
Regards, John Woodgate, OOO - Own Opinions Only.
There are two sides to every question, except
'What is a Moebius strip?'
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

xray · Mar 27, 2005

On Sun, 27 Mar 2005 12:59:27 +0100, John Woodgate
<jmw@jmwa.demon.contraspam.yuk> wrote:

On this basis, Jim, as a 'de facto idiot politically' clearly qualifies
for President! (;-)

I live in California. We have Arnold as our actual governor. The
"Governator". A wrestler Jessie Ventura, made it to office in a
northern state (sorry, I won't check now but I think Wisconsin - correct
me if.) Jim definitely could have a shot at political office here
somewhere in the US.

Sad but true.

xray · Mar 27, 2005

On Sun, 27 Mar 2005 13:20:34 GMT, xray <notreally@hotmail.invalid>
wrote:

I live in California. We have Arnold as our actual governor. The
"Governator". A wrestler Jessie Ventura, made it to office in a
northern state (sorry, I won't check now but I think Wisconsin - correct
me if.) Jim definitely could have a shot at political office here
somewhere in the US.

Sad but true.

Oh, and there was that actor guy Regan.

Jim Thompson · Mar 27, 2005

On Sun, 27 Mar 2005 12:59:27 +0100, John Woodgate
<jmw@jmwa.demon.contraspam.yuk> wrote:

I read in sci.electronics.design that xray <notreally@hotmail.invalid
wrote (in <4c1d41pd3sa35r8bkun5vavf0t6qaa3u90@4ax.com&gt about '2n7000
spice models', on Sun, 27 Mar 2005:

In the mean time, your talking trash against various parts of Europe
only helps to add to our ugly American image.

I think that's the thing that amuses me most, "xray" and those of his
ilk just don't get it... I don't give a rat's ass if I have an "ugly
American image" ;-)

Well, he gets attacked by European socialists, but I agree that his
retaliation is a bit puerile, just like parliamentary exchanges of
compliments.

Naaaah! Parliament-style banter is rude, and is that of Democrats...
shout down rather than debate. I always give you a chance to respond
without interruption... hell, I don't even read it ;-)

So you talk trash against our European allies, you supported a war that
was initated based on lies.

There's no point in opposing it now. It's done, and we have to bear the
consequences - getting Iraq back on its feet will be a LONG job.

Yep! Isn't it terrible, democracy is breaking out all over the Middle
East... because the rest of the shit-head dictators think they'll be
next (they will

Based on that I think you are a defacto idiot politically (maybe you
are intelligent otherwise).

See? That's the socialist way... disagree politically and be labeled.
I don't think "xray" is an idiot, just mal-informed.

Think about politicians (even in high office) for a bit. Do they not all
show signs of idiocy? Especially in terms of misbehaving in their
private lives and fondly expecting not to be found out? But not only
that; here in UK we are warming up for an election and what does the
(now 'former'!) Deputy Chairman of the Conservative Party do? Stands up
at a dinner and effectively says 'We are lying to the nation about our
plans for public spending cuts.' Can you imagine anything much more
stupid?

On this basis, Jim, as a 'de facto idiot politically' clearly qualifies
for President! (;-)

480)460-2350 | |
| E-mail Address at Website Fax

Clarence_A · Mar 27, 2005

"John Woodgate" wrote

xray wrote

<snip>

On this basis, Jim, as a 'de facto idiot politically' clearly
qualifies
for President! (;-)

Seconded!
I move for a vote!

Clarence_A · Mar 27, 2005

"Jim Thompson" wrote

I could never be elected President... I'm too un-PC.
...Jim Thompson

"un-PC" like Arnold S. he is actually opposing the Democrats and
corrupt practices, and they are really unhappy about it!

Jim Thompson · Mar 27, 2005

On Sun, 27 Mar 2005 18:15:05 GMT, "Clarence_A" <no@No.com> wrote:

"John Woodgate" wrote
xray wrote

snip

On this basis, Jim, as a 'de facto idiot politically' clearly
qualifies
for President! (;-)

Seconded!
I move for a vote!

You wouldn't want me for President...

(1) I'd blow Iran's nuc stuff away just about as fast as you could
blink.

(2) Likewise NK's.

(3) Syria is next.

(A) And I'd restore the GI bill and make our soldiers again feel
appreciated. (And train and arm them properly.)

(4) Any Imam who preached sedition would have his mosque promptly
leveled.

(5) I'd put France on the "No US citizen travel" list... and no
imports (maybe Germany as well ;-)

(6) I'd put a bounty out for al Qaeda so sweet that Pakistani's would
be turning in those clowns in body bags.

Did I miss offending anyone ?

480)460-2350 | |
| E-mail Address at Website Fax

John Woodgate · Mar 27, 2005

I read in sci.electronics.design that Jim Thompson
<thegreatone@example.com> wrote (in
<h9ud41dcqjlot1tu4i70614d81dfrf9mfi@4ax.com&gt

about '2n7000 spice
models', on Sun, 27 Mar 2005:

Did I miss offending anyone ?

Yes, me. I feel terribly neglected. (;-)
--
Regards, John Woodgate, OOO - Own Opinions Only.
There are two sides to every question, except
'What is a Moebius strip?'
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

Michael A. Terrell · Mar 27, 2005

John Woodgate wrote:

I read in sci.electronics.design that Jim Thompson
thegreatone@example.com> wrote (in
h9ud41dcqjlot1tu4i70614d81dfrf9mfi@4ax.com&gt about '2n7000 spice
models', on Sun, 27 Mar 2005:
Did I miss offending anyone ?

Yes, me. I feel terribly neglected. (;-)

You should be used to it. After all, you're British!

--
?

Michael A. Terrell
Central Florida

Michael A. Terrell · Mar 27, 2005

Jim Thompson wrote:

You wouldn't want me for President...

(1) I'd blow Iran's nuc stuff away just about as fast as you could
blink.

(2) Likewise NK's.

(3) Syria is next.

(A) And I'd restore the GI bill and make our soldiers again feel
appreciated. (And train and arm them properly.)

(4) Any Imam who preached sedition would have his mosque promptly
leveled.

(5) I'd put France on the "No US citizen travel" list... and no
imports (maybe Germany as well ;-)

(6) I'd put a bounty out for al Qaeda so sweet that Pakistani's would
be turning in those clowns in body bags.

Did I miss offending anyone ?

Jim Thompson

How about nuking Wanadoo.fr just for the hell of it? If you report
spam to them it bounces and claims you sent it to a different address.
What a chicken shit way of ducking responsibility for they sleazy
customers!

And what about Motorola?

--
?

Michael A. Terrell
Central Florida

Clarence_A · Mar 27, 2005

"Jim Thompson" <thegreatone@example.com> wrote in message
news:h9ud41dcqjlot1tu4i70614d81dfrf9mfi@4ax.com...

On Sun, 27 Mar 2005 18:15:05 GMT, "Clarence_A" <no@No.com
wrote:
"John Woodgate" wrote
xray wrote

snip
On this basis, Jim, as a 'de facto idiot politically' clearly
qualifies
for President! (;-)

Seconded!
I move for a vote!

You wouldn't want me for President...

(1) I'd blow Iran's nuc stuff away just about as fast as you
could
blink.

(2) Likewise NK's.

(3) Syria is next.

(A) And I'd restore the GI bill and make our soldiers again feel
appreciated. (And train and arm them properly.)

(4) Any Imam who preached sedition would have his mosque
promptly
leveled.

(5) I'd put France on the "No US citizen travel" list... and no
imports (maybe Germany as well ;-)

(6) I'd put a bounty out for al Qaeda so sweet that Pakistani's
would
be turning in those clowns in body bags.

Did I miss offending anyone ?
...Jim Thompson

So your to the left of me? Interesting.
Forgot to declare Martial law to clear the Illegals our of the US!

Jim Thompson · Mar 27, 2005

On Sun, 27 Mar 2005 20:14:22 GMT, "Clarence_A" <no@No.com> wrote:

"Jim Thompson" <thegreatone@example.com> wrote in message
news:h9ud41dcqjlot1tu4i70614d81dfrf9mfi@4ax.com...
On Sun, 27 Mar 2005 18:15:05 GMT, "Clarence_A" <no@No.com
wrote:
"John Woodgate" wrote
xray wrote

snip
On this basis, Jim, as a 'de facto idiot politically' clearly
qualifies
for President! (;-)

Seconded!
I move for a vote!

You wouldn't want me for President...

(1) I'd blow Iran's nuc stuff away just about as fast as you
could
blink.

(2) Likewise NK's.

(3) Syria is next.

(A) And I'd restore the GI bill and make our soldiers again feel
appreciated. (And train and arm them properly.)

(4) Any Imam who preached sedition would have his mosque
promptly
leveled.

(5) I'd put France on the "No US citizen travel" list... and no
imports (maybe Germany as well ;-)

(6) I'd put a bounty out for al Qaeda so sweet that Pakistani's
would
be turning in those clowns in body bags.

Did I miss offending anyone ?
...Jim Thompson

So your to the left of me? Interesting.
Forgot to declare Martial law to clear the Illegals our of the US!

480)460-2350 | |
| E-mail Address at Website Fax

Jim Thompson · Mar 28, 2005

On 28 Mar 2005 13:47:28 -0800, Winfield Hill
<hill_a@t_rowland-dotties-harvard-dot.s-edu> wrote:

Jim Thompson wrote...

Win, I've misplaced (or trashed) my copy of all those 2N7000 models.

I'll post them below.
Did you see my post this am, Message-ID: <d296a701865@drn.newsguy.com

----

Here're the 2n7000 models you posted, here on s.e.d., IIRC.
I had to modify some of them to run on Intusoft's spice.

Anasoft-1:

.SUBCKT 2N7000/PLP_XN _ssi_pin0_1 _ssi_pin1_2 _ssi_pin2_3
Cgs 2 3 12.3E-12
V_ssi_pin2 _ssi_pin2_3 3 0
V_ssi_pin1 _ssi_pin1_2 2 0
V_ssi_pin0 _ssi_pin0_1 1 0
Cgd1 2 4 27.4E-12
Cgd2 1 4 6E-12
M1 1 2 3 3 MOST1
M2 4 2 1 3 MOST2
D1 3 1 Dbody
.MODEL MOST1 NMOS(Level=3 Kp=20.78u W=9.7m L=2u Rs=20m Vto=2 Rd=1.186)
.MODEL MOST2 NMOS(VTO=-4.73 Kp=20.78u W=9.7m L=2u Rs=20m)
.MODEL Dbody D(Is=125f N=1.023 Rs=1.281 Ikf=18.01 Cjo=46.3p M=.3423
+ Vj=.4519 Bv=60 Ibv=10u Tt=161.6n)
.ENDS

Anasoft-2:

.SUBCKT 2N7000_XN _ssi_pin0_3 _ssi_pin1_4 _ssi_pin2_5
* Nodes D G S
V_ssi_pin2 _ssi_pin2_5 5 0
V_ssi_pin1 _ssi_pin1_4 4 0
V_ssi_pin0 _ssi_pin0_3 3 0
M1 3 2 5 5 MOD1
RG 4 2 343
RL 3 5 6E6
C1 2 5 23.5P
C2 3 2 4.5P
D1 5 3 DIODE1
*
.MODEL MOD1 NMOS VTO=2.474 RS=1.68 RD=0.0 IS=1E-15 KP=0.296
+CBD=53.5P PB=1 LAMBDA=267E-6
.MODEL DIODE1 D IS=1.254E-13 N=1.0207 RS=0.222
.END 2N7000

Supertex

.MODEL 2N7000 NMOS (LEVEL=3 RS=0.205 NSUB=1.0E15
+DELTA=0.1 KAPPA=0.0506 TPG=1 CGDO=3.1716E-9
+RD=0.239 VTO=1.000 VMAX=1.0E7 ETA=0.0223089
+NFS=6.6E10 TOX=1.0E-7 LD=1.698E-9 UO=862.425
+XJ=6.4666E-7 THETA=1.0E-5 CGSO=9.09E-9 L=2.5E-6
+W=0.8E-2)
.ENDS

Philips:

.SUBCKT 2N7000/PLP 1 2 3
Cgs 2 3 12.3E-12
Cgd1 2 4 27.4E-12
Cgd2 1 4 6E-12
M1 1 2 3 3 MOST1
M2 4 2 1 3 MOST2
D1 3 1 Dbody
.MODEL MOST1 NMOS(Level=3 Kp=20.78u W=9.7m L=2u Rs=20m Vto=2 Rd=1.186)
.MODEL MOST2 NMOS(VTO=-4.73 Kp=20.78u W=9.7m L=2u Rs=20m)
.MODEL Dbody D(Is=125f N=1.023 Rs=1.281 Ikf=18.01 Cjo=46.3p M=.3423
+ Vj=.4519 Bv=60 Ibv=10u Tt=161.6n)
.ENDS

Ancient MicroSim:

.model M2n7000 NMOS(Level=3 Gamma=0 Delta=0 Eta=0 Theta=0 Kappa=0.2
+ Vmax=0 Xj=0 Tox=2u Uo=600 Phi=.6 Kp=1.073u W=.12 L=2u Rs=20m
+ Vto=1.73 Rd=.5489 Rds=48MEG Cgso=73.61p Cgdo=6.487p Cbd=74.46p Mj=.5
+ Pb=.8 Fc=.5 Rg=546.2 Is=10f N=1 Rb=1m)

Zetex:

.SUBCKT M2N7000/ZTX 3 4 5
* Nodes D G S
M1 3 2 5 5 MOD1
RG 4 2 343
RL 3 5 6E6
D1 5 3 DIODE1
.MODEL MOD1 NMOS VTO=2.474 RS=1.68 RD=0.0 IS=1E-15 KP=0.296
+CGSO=23.5P CGDO=4.5P CBD=53.5P PB=1 LAMBDA=267E-6
.MODEL DIODE1 D IS=1.254E-13 N=1.0207 RS=0.222
.ENDS

---------

I've found two others, from Motorola originally I think.

.MODEL MN7000 NMOS (LEVEL=1 VTO=2.4 KP=.17 GAMMA=1.76U
+ PHI=.75 LAMBDA=1.25M RD=.35 RS=.448 IS=41.6F PB=.8 MJ=.46
+ CBD=44.4P CBS=53.3P CGSO=24N CGDO=20N CGBO=116N)
* -- Assumes default L=100U W=100U --
* 60 Volt .2 Amp 2.5 ohm Enh-Mode N-Channel MOS-FET 11-19-1990

.MODEL 2N7002LT1 NMOS LEVEL=1 AF=1E-26 CBD=0 CBS=0 CGBO=0
+ CGDO=0 CGSO=0 FC=0.5 GAMMA=3 KF=1.2 KP=0.104475 LAMBDA=0
+ LD=0 MJ=0.5 PB=0.75 PHI=0.554054 RD=0.593226 RS=0.593226
+ VTO=1.92518

480)460-2350 | |
| E-mail Address at Website Fax

Jim Thompson · Mar 28, 2005

Here's the skinny...

Level=3 CAN't model subthreshold, period.

The model definition is Id = 0 for Vgs < Vth.

So, until manufacturers start using BSIM3 for power FET's you are
stuck.

I have put in a request for a translator, Level=3 to Level=7 (49 in
HSpice), which could provide me with a baseline upon which to build an
accurate powerFET model.

However, don't hold your breath... my contact was less than
optimistic.

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice

480)460-2350 | |
| E-mail Address at Website Fax

Jim Thompson · Mar 28, 2005

Win, See...

Newsgroups: alt.binaries.schematics.electronic
Subject: 2N7000 Modeling Issues - Test2N7000-Level7.pdf
Message-ID: <703h41d0tcvctdfoqar06vpjd1525hpsq6@4ax.com>

This is an XFAB, Level=7, model.

But even it seems to have an artificially flattened bottom end.

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice

480)460-2350 | |
| E-mail Address at Website Fax

Winfield Hill · Mar 28, 2005

Jim Thompson wrote...

Win, See...

Newsgroups: alt.binaries.schematics.electronic
Subject: 2N7000 Modeling Issues - Test2N7000-Level7.pdf
Message-ID: <703h41d0tcvctdfoqar06vpjd1525hpsq6@4ax.com

This is an XFAB, Level=7, model.

What does the entire model expression look like for your plot?
I can run Bsim3v2 level 7 and Bsim3v3.1 level 8, etc.

But even it seems to have an artificially flattened bottom end.

Perhaps it simply has an artificially-high 250pA leakage term.

The measured minimum current on my part was less than 2pA with
Vgs = 0 and Vds = 5V (I need to repeat the measurement, after
zeroing the instrument, so I how much was instrument leakage and
zero-offset error, vs actual 2n7000 component Id leakage at 5V).
For design purposes, maybe they feel one shouldn't count on such
low leakage. For myself, I'd prefer to add it back explicitly.

--
Thanks,
- Win

Jim Thompson · Mar 28, 2005

On 28 Mar 2005 15:42:46 -0800, Winfield Hill
<hill_a@t_rowland-dotties-harvard-dot.s-edu> wrote:

Jim Thompson wrote...

Win, See...

Newsgroups: alt.binaries.schematics.electronic
Subject: 2N7000 Modeling Issues - Test2N7000-Level7.pdf
Message-ID: <703h41d0tcvctdfoqar06vpjd1525hpsq6@4ax.com

This is an XFAB, Level=7, model.

What does the entire model expression look like for your plot?

See...

Newsgroups: alt.binaries.schematics.electronic
Subject: Re: 2N7000 Modeling Issues - Test2N7000-Level7.pdf -
Test2N7000-Level7-5V.pdf
Message-ID: <3a7h411ua171vsosvb3gl9t7011cctcq7a@4ax.com>

I can run Bsim3v2 level 7 and Bsim3v3.1 level 8, etc.

But even it seems to have an artificially flattened bottom end.

Perhaps it simply has an artificially-high 250pA leakage term.

The measured minimum current on my part was less than 2pA with
Vgs = 0 and Vds = 5V (I need to repeat the measurement, after
zeroing the instrument, so I how much was instrument leakage and
zero-offset error, vs actual 2n7000 component Id leakage at 5V).
For design purposes, maybe they feel one shouldn't count on such
low leakage. For myself, I'd prefer to add it back explicitly.

I'm bound to non-disclosure on the models (this device is simply
scaled from a _current_ project).

So I'll study the model and see what parameters move what, until I get
a DC match to 2N7000, then add in the capacitances from a 2N7000 and
see how close we get.

Or bug the manufacturer to make a Level=7 model ;-)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice

480)460-2350 | |
| E-mail Address at Website Fax

Winfield Hill · Mar 29, 2005

Jim Thompson wrote...

Winfield Hill wrote:

What does the entire model expression look like for your plot?

See...

Newsgroups: alt.binaries.schematics.electronic
Subject: Re: 2N7000 Modeling Issues - Test2N7000-Level7.pdf -
Test2N7000-Level7-5V.pdf
Message-ID: <3a7h411ua171vsosvb3gl9t7011cctcq7a@4ax.com

That's not helpful. You've got an 87mV/decade slope for the MOSFET,
are you sure any fab MOSFET really has such a high transconductance?
It looks like a draftsman's artificially-too-good plot to me.

I'm bound to non-disclosure on the models (this device is simply
scaled from a _current_ project).

So I'll study the model and see what parameters move what, until
I get a DC match to 2N7000, then add in the capacitances from a
2N7000 and see how close we get.

That's good, the parameters you're using dramatically fail to match
the real 2n7000. But anyway it's good to see a subthreshold plot...

Or bug the manufacturer to make a Level=7 model ;-)

Nah, won't happen.

--
Thanks,
- Win

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