ngspice-devel — Ngspice development list (developers are here).

Re: [Ngspice-devel] Adding idmult

[Brian D. <deg...@gm...>]

M. Vogt,

I look into that too.  HSPICE is basically what I use for everything
commercial because it's "fab approved", but ngspice has a lot of advantages
because of my academic overlap, so I have an odd incentive to make
everything compatible.
To that end, I still owe you guys some integration examples into verilog.
I'm trying to make sure that all of the division lines between my projects
are very bright, and my last foray into making something openly available
was a bit hazy.

Sincerely,
Brian Degnan, Ph.D.



On Tue, Sep 30, 2025 at 6:27 AM Holger Vogt <hol...@un...> wrote:

> If you are using BSIM-4.8.3, the current version, you will find instance
> parameters
>
> mult_i "Variability in current"
> mult_q "Variability in charge"
> mult_fn "Variability in flicker noise"
>
> That may do what you want.
>
>
> _______________________________________________
> Ngspice-devel mailing list
> Ngs...@li...
> https://lists.sourceforge.net/lists/listinfo/ngspice-devel
>

Re: [Ngspice-devel] Adding idmult

[Holger V. <hol...@un...>]

If you are using BSIM-4.8.3, the current version, you will find instance 
parameters

mult_i "Variability in current"
mult_q "Variability in charge"
mult_fn "Variability in flicker noise"

That may do what you want.

Re: [Ngspice-devel] Adding idmult

[Kevin Z. <kev...@gm...>]

Brain,

Thanks for the additional context. Otherwise I would be suspicious why 
somebody wouldn't "just" use the multiplier :)

I suspect you'll just have to hand hack the model.

The device models are located in: src/spicelib/devices

There are a few BSIM4 directories corresponding to different model 
versions, make sure you're editing the right one.

Add your parameter to b4.c, then edit all of the *ld.c files. (If you're 
not familiar with SPICE, these are the modules that "load" the device 
currents into the circuit matrix, and there are dc/ac/pz analysis 
versions that all need to be consistent).

You'll have to wait for the project maintainer to weigh in to see if a 
model change would be accepted upstream... but of course you can always 
use your own modifications (at your own risk!)

Finally, it sounds like your underlying model is BSIM 4, but if it's 
actually something like PSP you can use ngpsice/OSDI and OpenVAF to run 
VerilogA models.

Regards,
Kevin

Re: [Ngspice-devel] Adding idmult

[Brian D. <deg...@gm...>]

Kevin,

I'm sorry, I misspoke. The drain current multiplier that I wanted to add
is MULID0 (idmult is what we call it colloquially).
MULID0 lets me do a sensitivity analysis on bias and gain while holding
Cd/Cs/Cg steady.   It also lets me tweak simulations vs. measured silicon.
I use BSIM models supplied by a "commercially available 2nm" process (as
well as the PSP models depending).
In HSPICE, MULID0 exists for BSIM4, but I suspect it's because it's
supported in PSP103.0, Level=69.

The general syntax for my BSIM4 model is:
Mxxx nd ng ns [nb] mname [L=val] [W=val] [M=val]
+ [AD=val] [AS=val] [PD=val] [PS=val]
+ [RGATEMOD=val] [RBODYMOD=val] [TRNQSMOD=val]
+ [ACNQSMOD=val] [GEOMOD=val] [RGEOMOD=val]
+ [NRS=val] [NRD=val] [RBPB=val] [RBPD=val]
+ [RBPS=val] [RBDB=val] [RBSB=val] [NF=val]
+ [MIN=val] [RDC=val] [RSC=val] [DELVTO=val]
+ [MULU0=val] [DELK1=val] [DELNFCT=val]
+ [DELTOX=val] [OFF] [IC=Vds, Vgs, Vbs]
+ [WNFLAG=val] [MULID0=val]

The fact that MULID0 is the last thing, makes me think that it was
definitely added later.
I can say for sure that it wasn't in HSPICE when I was in grad school, but
it was there in 2015 when I was doing SOI work.

Anyway, I would be excited to get this into the BSIM4 model on ngspice.   I
just have no idea what the level of effort is.  Honestly, I could probably
take a stab at it.

Sincerely,
Brian Degnan, Ph.D.



On Mon, Sep 29, 2025 at 3:58 PM Kevin Zheng <kev...@gm...> wrote:

> Hi Brian,
>
> I'm not sure I've heard of an idmult parameter in HSPICE. Is this a
> standard HSPICE parameter, or a parameter to the particular transistor
> model that you are using?
>
> (Which transistor model are you using? BSIM? EKV?)
>
> I also don't understand what you mean when you say you "don't want to
> change the bias point." It seems to me that setting M would do the same
> as multiplying the drain current.
>
> Regards,
> Kevin
>

Re: [Ngspice-devel] Adding idmult

[Kevin Z. <kev...@gm...>]

Hi Brian,

I'm not sure I've heard of an idmult parameter in HSPICE. Is this a
standard HSPICE parameter, or a parameter to the particular transistor
model that you are using?

(Which transistor model are you using? BSIM? EKV?)

I also don't understand what you mean when you say you "don't want to
change the bias point." It seems to me that setting M would do the same
as multiplying the drain current.

Regards,
Kevin

[Ngspice-devel] Adding idmult

[Brian D. <deg...@gm...>]

Hello,

I've been using ngspice concurrently with HSPICE for some of my models.
In HSPICE, I have idmult, which just multiplies the drain current.   I
cannot use "m" as I don't want to change the bias point.  My motivation is
so that my HSPICE/ngspice card decks are the same.

Does anyone have any thoughts on this?  I have no idea the level of effort
for this.

Sincerely,
Brian Degnan, Ph.D.

Re: [Ngspice-devel] ngspice-44 build failure on cygwin

[Holger V. <hol...@un...>]

Marco,

ngspice-44.2 is available.

This is a bug-fix release, fixing some build issues and some recently 
removed source code bugs.

Regards

Holger

Re: [Ngspice-devel] ngspice-44 build failure on cygwin

[Marco A. <mar...@gm...>]

On 10/01/2025 19:48, Holger Vogt wrote:
> Marco,
> 
> you may need to build the standard ngspice.exe with
> 
> --with-readline=no
> --with-editline=yes
> 
> I have always tested building on Cygwin with readline. I will check 
> editline as well.
> 
> Holger
> 

build on the bot went fine
https://cygwin.com/cgi-bin2/jobs.cgi?id=9221

and that package is deployed in the distribution

Regards
Marco

Re: [Ngspice-devel] ngspice-44 build failure on cygwin

[Marco A. <mar...@gm...>]

On 10/01/2025 16:31, Holger Vogt wrote:
> Concerning the configure options:
> 
> Since ngspice-43 several options are included automatically:
> --enable-xspice, --enable-openmp, --enable-osdi, --enable-klu, --with- 
> readline=yes
> 
> option may be deselected for example by --disable-openmp, with-readline=no
> 
> When the shared ngspice libarary is to be made using --with-ngshared,
> neither readline nor editline options are required, as there is no 
> command input by users.


Cheking the configure --help , I noticed that is NOT obvious that
openmp is enabled by default as two lines are present

   --enable-openmp         Use OpenMP parallel processing
   --disable-openmp        do not use OpenMP

while for the others is more clear

  --disable-xspice        Disable XSPICE enhancements
  --disable-osdi          Disable OSDI integration
  --disable-klu           Use KLU linear systems solver. Default=yes.
                                                         ^^^^^^^^^^^^
partially misleading  default 😉

Regards
Marco

Re: [Ngspice-devel] ngspice-44 build failure on cygwin

[Holger V. <hol...@un...>]

Marco,

you may need to build the standard ngspice.exe with

--with-readline=no
--with-editline=yes

I have always tested building on Cygwin with readline. I will check 
editline as well.

Holger



Am 10.01.2025 um 19:06 schrieb Marco Atzeri:
> On 10/01/2025 16:31, Holger Vogt wrote:
>> Concerning the configure options:
>>
>> Since ngspice-43 several options are included automatically:
>> --enable-xspice, --enable-openmp, --enable-osdi, --enable-klu, --with- 
>> readline=yes
>>
>> option may be deselected for example by --disable-openmp, with- 
>> readline=no
>>
>> When the shared ngspice libarary is to be made using --with-ngshared,
>> neither readline nor editline options are required, as there is no 
>> command input by users.
>>
> 
> Hi Holger,
>   I saw a configure failure for the shared library on the builder bot
> as the readline was not present.
> You may need to check it.
> 
> By long time the cygwin build is using the editline, I never looked to 
> change it until now.
> 
> I patched manually the code along the proposed patch and the shared 
> build worked. The standard one is still running but I expect same result
> 
> Regrds
> Marco
> 

Re: [Ngspice-devel] ngspice-44 build failure on cygwin

[Marco A. <mar...@gm...>]

On 10/01/2025 16:31, Holger Vogt wrote:
> Concerning the configure options:
> 
> Since ngspice-43 several options are included automatically:
> --enable-xspice, --enable-openmp, --enable-osdi, --enable-klu, --with- 
> readline=yes
> 
> option may be deselected for example by --disable-openmp, with-readline=no
> 
> When the shared ngspice libarary is to be made using --with-ngshared,
> neither readline nor editline options are required, as there is no 
> command input by users.
> 

Hi Holger,
  I saw a configure failure for the shared library on the builder bot
as the readline was not present.
You may need to check it.

By long time the cygwin build is using the editline, I never looked to 
change it until now.

I patched manually the code along the proposed patch and the shared 
build worked. The standard one is still running but I expect same result

Regrds
Marco

Re: [Ngspice-devel] ngspice-44 build failure on cygwin

[Holger V. <hol...@un...>]

Concerning the configure options:

Since ngspice-43 several options are included automatically:
--enable-xspice, --enable-openmp, --enable-osdi, --enable-klu, 
--with-readline=yes

option may be deselected for example by --disable-openmp, with-readline=no

When the shared ngspice libarary is to be made using --with-ngshared,
neither readline nor editline options are required, as there is no 
command input by users.

Re: [Ngspice-devel] ngspice-44 build failure on cygwin

[Holger V. <hol...@un...>]

The patch is available in the ngspice git master branch.

Do you have a chance to check if it is o.k?

I would then prepare a bug fix release tagged ngspice44.2.

Re: [Ngspice-devel] ngspice-44 build failure on cygwin

[Holger V. <hol...@un...>]

Thanks for the report.

There is already a patch for this bug under way.

diff --git a/src/xspice/verilog/Makefile.am b/src/xspice/verilog/Makefile.am
index cd7674934..262d63384 100644
--- a/src/xspice/verilog/Makefile.am
+++ b/src/xspice/verilog/Makefile.am
@@ -19,11 +19,11 @@ initdata2_DATA = ../../include/ngspice/cosim.h \

  pkglib_LTLIBRARIES = ivlng.la ivlngvpi.la
  ivlng_la_SOURCES = icarus_shim.c icarus_shim.h coroutine_shim.h
-ivlng_la_CFLAGS = -I../../../../src/include
+ivlng_la_CFLAGS = -I$(top_srcdir)/src/include
  ivlng_la_LDFLAGS = -module -shared -avoid-version

  ivlngvpi_la_SOURCES = vpi.c icarus_shim.h vpi_user_dummy.h coroutine.h 
coroutine_cosim.h
-ivlngvpi_la_CFLAGS = -I../../../../src/include
+ivlngvpi_la_CFLAGS = -I$(top_srcdir)/src/include
  ivlngvpi_la_LDFLAGS = -module -shared  -avoid-version

[Ngspice-devel] ngspice-44 build failure on cygwin

[Marco A. <mar...@gm...>]

Building on separate tree from source the build stop at:


make[3]: Entering directory 
'/pub/devel/ngspice/ngspice-44-1.x86_64/build/ngshared/src/xspice/verilog'
   CC       ivlng_la-icarus_shim.lo
/pub/devel/ngspice/ngspice-44-1.x86_64/src/ngspice-44/src/xspice/verilog/icarus_shim.c:21:10: 
fatal error: ngspice/cmtypes.h: No such file or directory
    21 | #include "ngspice/cmtypes.h" // For Digital_t
       |          ^~~~~~~~~~~~~~~~~~~
compilation terminated.


configured with

                 --prefix=/usr \
                 --enable-xspice \
                 --enable-cider \
                 --enable-openmp \
                 --enable-osdi \
                 --enable-klu \
                 --with-editline=yes \
                 --with-ngshared


for what I see the file is in an expected location in the source tree

$ find ngspice-44-1.x86_64 -name cmtypes.h
ngspice-44-1.x86_64/origsrc/ngspice-44/src/include/ngspice/cmtypes.h
ngspice-44-1.x86_64/src/ngspice-44/src/include/ngspice/cmtypes.h


but the the Makefile.am of that verilog directory
is not written with proper declaration for separate tree:

marco@LAPTOP-MK4Q85AK 
/pub/devel/ngspice/ngspice-44-1.x86_64/build/ngshared/src/xspice/verilog
x86_64 $ make V=1
/bin/sh ../../../libtool  --tag=CC   --mode=compile gcc -DHAVE_CONFIG_H 
  -I. 
-I/pub/devel/ngspice/ngspice-44-1.x86_64/src/ngspice-44/src/xspice/verilog 
-I../../../src/include  -I../../../../src/include -ggdb -O2 -pipe -Wall 
-Werror=format-security -Wp,-D_FORTIFY_SOURCE=3 -fstack-protector-strong 
--param=ssp-buffer-size=4 
-ffile-prefix-map=/pub/devel/ngspice/ngspice-44-1.x86_64/build=/usr/src/debug/ngspice-44-1 
-ffile-prefix-map=/pub/devel/ngspice/ngspice-44-1.x86_64/src/ngspice-44=/usr/src/debug/ngspice-44-1 
-std=gnu11 -fopenmp -MT ivlng_la-icarus_shim.lo -MD -MP -MF 
.deps/ivlng_la-icarus_shim.Tpo -c -o ivlng_la-icarus_shim.lo `test -f 
'icarus_shim.c' || echo 
'/pub/devel/ngspice/ngspice-44-1.x86_64/src/ngspice-44/src/xspice/verilog/'`icarus_shim.c
libtool: compile:  gcc -DHAVE_CONFIG_H -I. 
-I/pub/devel/ngspice/ngspice-44-1.x86_64/src/ngspice-44/src/xspice/verilog 
-I../../../src/include -I../../../../src/include -ggdb -O2 -pipe -Wall 
-Werror=format-security -Wp,-D_FORTIFY_SOURCE=3 -fstack-protector-strong 
--param=ssp-buffer-size=4 
-ffile-prefix-map=/pub/devel/ngspice/ngspice-44-1.x86_64/build=/usr/src/debug/ngspice-44-1 
-ffile-prefix-map=/pub/devel/ngspice/ngspice-44-1.x86_64/src/ngspice-44=/usr/src/debug/ngspice-44-1 
-std=gnu11 -fopenmp -MT ivlng_la-icarus_shim.lo -MD -MP -MF 
.deps/ivlng_la-icarus_shim.Tpo -c 
/pub/devel/ngspice/ngspice-44-1.x86_64/src/ngspice-44/src/xspice/verilog/icarus_shim.c 
  -DDLL_EXPORT -DPIC -o .libs/ivlng_la-icarus_shim.o
/pub/devel/ngspice/ngspice-44-1.x86_64/src/ngspice-44/src/xspice/verilog/icarus_shim.c:21:10: 
fatal error: ngspice/cmtypes.h: No such file or directory
    21 | #include "ngspice/cmtypes.h" // For Digital_t
       |          ^~~~~~~~~~~~~~~~~~~
compilation terminated.
make: *** [Makefile:538: ivlng_la-icarus_shim.lo] Error 1

[Ngspice-devel] Qucs-S 24.3.2 release

[Vadim K. <ra...@gm...>]

Hello Qucs and Ngspice developer,

The Qucs-S v24.3.2 has been released. This version contains no new 
features, only fixed a critical bug: 
https://github.com/ra3xdh/qucs_s/issues/948

The release page is available here: 
https://github.com/ra3xdh/qucs_s/releases/tag/24.3.2
Installation instructions: 
https://github.com/ra3xdh/qucs_s/wiki/Installation

Regards,
Vadim Kuznetsov

[Ngspice-devel] Qucs-S 24.3.1 release

[Vadim K. <ra...@gm...>]

Hello Qucs and Ngspice developer,

The Qucs-S v24.3.1 has been released. This version contains no new 
features, only bugfixes and small improvements. Fixed some critical bugs 
in plotting subsystem. The release packages has been built automatically 
using Github CI actions.

See the release notes and download links here: 
https://github.com/ra3xdh/qucs_s/releases/tag/24.3.1
The discussion page is here: 
https://github.com/ra3xdh/qucs_s/discussions/937
Installation instructions: 
https://github.com/ra3xdh/qucs_s/wiki/Installation

Regards,
Vadim Kuznetsov

[Ngspice-devel] Qucs-S v24.3.0 release

[Vadim K. <ra...@gm...>]

Hello Qucs and Ngspice developers,

I am glad to present a new Qucs-S v21.3.0 release. The packages and 
installation instructions could be found at the release page: 
https://github.com/ra3xdh/qucs_s/releases/tag/24.3.0

This release contains a number of important improvements. Here are the 
main features added in v24.3.0:

* SpiceLibComp redesign. This device is renamed to /Spice Library 
Device/ and provides an easy way
to add SPICE model to schematic and assign symbol to it.
* Added possibity to import SPICE model for Diode, BJT, MOSFET, and JFET 
unified devices using special button in component properties
* Implemented symbol files editing
* Redesign of schematic rendering engine. Improve rendering quality on 
HiDPI displays
* Improved Qucsconv GUI to reflect new converter features
* Fixed ASCO operation using QucsatorRF
* QucsatorRF updated to version 1.0.1 This update mainly related to file 
formats comverter See 
https://github.com/ra3xdh/qucsator_rf/releases/tag/v1.0.1 for release notes
* Linux and WIndows binary packages switched to Qt6
* Implemented MacOS installation support using homebrew
* Introduced continuous releases

The full changelog could be found at the release page: 
https://github.com/ra3xdh/qucs_s/releases/tag/24.3.0 The Qucs-S package 
is not related to the recent revival of the old Qucs development.

Regards,
Vadim Kuznetsov

Re: [Ngspice-devel] mosfet model of the differential amplifier

[Sourav C. <sou...@gm...>]

Thank you all for your help. I will refer to pspice manual.

On Wed, May 29, 2024 at 3:12 AM Holger Vogt <hol...@un...> wrote:

> ngspice offers more than 20 MOSFET models (see ngspice manual chapter
> 11.2).
>
> The user determines which model is selected, by providing suitable model
> paramaters with level and version information.
>
> All models can be used to simulate a differential amplifier.
>
> Skywater PDK simulation uses the BSIM4 MOS model, the parameters are
> provided by the PDK. Its equations are described in a user manual
> https://ngspice.sourceforge.io/external-documents/models/BSIM480_Manual.pdf.
>
> The equations are complex and not useful for hand calculation.
>
> The most simple model is the MOS1 model, unfortunately not suited for
> modern MOS processes. Its equations are described in the PSPICE manual
> https://www.seas.upenn.edu/~jan/spice/PSpice_ReferenceguideOrCAD.pdf on
> page 198.
>
>
> _______________________________________________
> Ngspice-devel mailing list
> Ngs...@li...
> https://lists.sourceforge.net/lists/listinfo/ngspice-devel
>

Re: [Ngspice-devel] mosfet model of the differential amplifier

[Holger V. <hol...@un...>]

ngspice offers more than 20 MOSFET models (see ngspice manual chapter 11.2).

The user determines which model is selected, by providing suitable model 
paramaters with level and version information.

All models can be used to simulate a differential amplifier.

Skywater PDK simulation uses the BSIM4 MOS model, the parameters are 
provided by the PDK. Its equations are described in a user manual 
https://ngspice.sourceforge.io/external-documents/models/BSIM480_Manual.pdf. 
The equations are complex and not useful for hand calculation.

The most simple model is the MOS1 model, unfortunately not suited for 
modern MOS processes. Its equations are described in the PSPICE manual 
https://www.seas.upenn.edu/~jan/spice/PSpice_ReferenceguideOrCAD.pdf on 
page 198.

[Ngspice-devel] mosfet model of the differential amplifier

[Sourav C. <sou...@gm...>]

Hello ngspice Developers,
       I want to know what spice model is used in differential amplifier
with mosfet. Because in diff amp you are applying different voltage to gate
of mosfet. One mosfet going into saturation other going into cut-off. I
want to know what equation or model is used in simulating above behaviour.
In both cases you are applying gate voltages which are above threshold
voltage.

Thank you again for your help and I  look forward to hearing from you soon.
With warm regards,
Sourav Chatterjee

Re: [Ngspice-devel] Qucs-S 24.2.0 release

[Vadim K. <ra...@gm...>]

Hello Qucs and Ngspice developers,

I have recently prepared Qucs-S v24.2.1 hotfix release. This release 
contains no new features except the fix for the critical bug with DC 
bias simulation and the fix of Fedora RPM package build failure. See the 
release notes: https://github.com/ra3xdh/qucs_s/releases/tag/24.2.1

Regards,
Vadim Kuznetsov

On 25.03.24 21:55, Vadim Kuznetsov wrote:
> Hello Qucs and Ngspice developers,
>
> I am glad to present a new Qucs-S v24.2.0 release. The packages and 
> installation instructions could be found at the release page: 
> https://github.com/ra3xdh/qucs_s/releases/tag/24.2.0
>
> This release contains a number of important improvements. Here are the 
> main features added in v24.2.0:
>
> * QucsatorRF is now a part of the package; no need to compile and 
> install qucsator manually;
> * Qucs-RFLayout tool could be launched from Tools menu; this tool must 
> be installed separately. Refer to 
> https://github.com/thomaslepoix/Qucs-RFlayout
> * Redesign of the Qucsconv GUI
> * Matching tool backported from unreleased Qucs-0.0.20
> * Added RF devices group; backported different RF devices for Qucsator
>
> The full changelog could be found at the release page.
>
> Regards,
> Vadim Kuznetsov

[Ngspice-devel] Qucs-S 24.2.0 release

[Vadim K. <ra...@gm...>]

Hello Qucs and Ngspice developers,

I am glad to present a new Qucs-S v24.2.0 release. The packages and 
installation instructions could be found at the release page: 
https://github.com/ra3xdh/qucs_s/releases/tag/24.2.0

This release contains a number of important improvements. Here are the 
main features added in v24.2.0:

* QucsatorRF is now a part of the package; no need to compile and 
install qucsator manually;
* Qucs-RFLayout tool could be launched from Tools menu; this tool must 
be installed separately. Refer to 
https://github.com/thomaslepoix/Qucs-RFlayout
* Redesign of the Qucsconv GUI
* Matching tool backported from unreleased Qucs-0.0.20
* Added RF devices group; backported different RF devices for Qucsator

The full changelog could be found at the release page.

Regards,
Vadim Kuznetsov

[Ngspice-devel] Qucs-S 24.1.0 release

[Vadim K. <ra...@gm...>]

Hello Qucs and Ngspice developers,

I am glad to present a new Qucs-S v21.1.0 release. The packages and 
installation instructions could be found at the release page: 
https://github.com/ra3xdh/qucs_s/releases/tag/24.1.0

This release contains a number of important improvements. Here are the 
main features added in v24.1.0:

* Ngspice simulation support rework
* Added new devices
* Massive update of the libraries; added analog ICs libraries
* Added new RF features including RLCG support for SPICE
* Many HiDPI displays support improvements

The full changelog could be found at the release page.

Regards,
Vadim Kuznetsov

[Ngspice-devel] Federated Simulation

[Kevin C. <cam...@gm...>]

Just FYI -

https://www.accellera.org/news/press-releases/382-accellera-announces-proposed-working-group-to-explore-federated-simulation-standard

If anyone is interested in making a highly parallel multi-domain simulation
system using open source simulators, let me know.

Regards,
Kev.