help about a SPICE model

jeko · Mar 20, 2005

Hi,
I'm an computer science student and I have a problem. I have a picture
(and scientific articles) of a 2nd order biquad lowpass filter and I
would want (is necessary) write a spice model of this circuit but I'm
not able. Is there someone that courteously could convert this circuit
design in SPICE code?

thanks

Andrea

Jim Thompson · Mar 20, 2005

On Sun, 20 Mar 2005 18:31:22 +0100, jeko <a.napoleoni@fastwebnet.it>
wrote:

Hi,
I'm an computer science student and I have a problem. I have a picture
(and scientific articles) of a 2nd order biquad lowpass filter and I
would want (is necessary) write a spice model of this circuit but I'm
not able. Is there someone that courteously could convert this circuit
design in SPICE code?

thanks

Andrea

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

jeko · Mar 20, 2005

I must use SPICE 3f5 Berkeley version on linux system.
this is the link of my schematic design
http://tinypic.com/2aeyo0

thanx

Andrea

Jim Thompson ha scritto:

On Sun, 20 Mar 2005 18:31:22 +0100, jeko <a.napoleoni@fastwebnet.it
wrote:

Hi,
I'm an computer science student and I have a problem. I have a picture
(and scientific articles) of a 2nd order biquad lowpass filter and I
would want (is necessary) write a spice model of this circuit but I'm
not able. Is there someone that courteously could convert this circuit
design in SPICE code?

thanks

Andrea

Post a schematic on alt.binaries.schematics.electronic

Which Spice variant are you using? The "code" can vary some, from
simulator to simulator.

...Jim Thompson

Jim Thompson · Mar 21, 2005

On Sun, 20 Mar 2005 19:24:24 +0100, jeko <a.napoleoni@fastwebnet.it>
wrote:

I must use SPICE 3f5 Berkeley version on linux system.
this is the link of my schematic design
http://tinypic.com/2aeyo0

thanx

Andrea

[snip]

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

Mike Monett · Mar 21, 2005

jeko wrote:

I must use SPICE 3f5 Berkeley version on linux system.
this is the link of my schematic design
http://tinypic.com/2aeyo0

thanx

Andrea

I believe LTSpice runs under WINE. You can get it here along with SPICE
models:

http://www.linear.com/company/software.jsp

Regards,

Mike Monett

jeko · Mar 21, 2005

Jim Thompson ha scritto:

On Sun, 20 Mar 2005 19:24:24 +0100, jeko <a.napoleoni@fastwebnet.it
wrote:

I must use SPICE 3f5 Berkeley version on linux system.
this is the link of my schematic design
http://tinypic.com/2aeyo0

thanx

Andrea

[snip]

Your schematic design has no values for the components. What
frequency response is it to have?

...Jim Thompson

"..The opamp model has an open loop gain of 10000.the output voltage
restriction is -1.5V +1.5V and the maximum output current is 80mA. Due
to these restrictions the whole system is nonlinear. This circuit has
two state variables, namely the capacitor voltages Vc1 and Vc2. Using
acharge oriented capacitor model willnormally lead to the two charges as
state variables. We changed this, because we found it more convenientto
think in voltages than in charges.The corner frequency Wc and the
damping factor d ar given by Wc = (Sqrt(R1*R2*C1*C2))^-1 and d =
0.5C1Wc(R1+R2). We use two different value sets for the resistors and
capacitors, one with Wc =100s^-1 and d = 0.5 and the second one at the
same frequency but with d = 2.Tus, we get twoequivalent lowpass filters
differing only by the damping factor.
The property to be checked in this example is the occurrence of
overschooting in the two filters. Since these properties should be
proved for arbitrary input signals, the appropriate input value model si
chosen. The input signal range is Vin =[-2..2] so that the nonliearity
due to the restricted output voltage will effect the system beahviour.
The state space is restricted to Vc1=[-4..4] and Vc2[-2.5 .. 2.5].Vin
start from 0."
Obviously I will change manually the variables values that I have writen
above
Thanx
Andrea

jeko · Mar 21, 2005

Mike Monett ha scritto:

jeko wrote:

I must use SPICE 3f5 Berkeley version on linux system.
this is the link of my schematic design
http://tinypic.com/2aeyo0

thanx

Andrea

I believe LTSpice runs under WINE. You can get it here along with SPICE
models:

http://www.linear.com/company/software.jsp

Regards,

Mike Monett

Thank you, but I'm obliged to use only SPICE 3f5 (3f2 or higher) on
linux system.

A.

Winfield Hill · Mar 21, 2005

jeko wrote...

Mike Monett ha scritto:
jeko wrote:

I must use SPICE 3f5 Berkeley version on linux system.

Thank you, but I'm obliged to use only SPICE 3f5 (3f2 or higher)
on linux system.

Most of us like to use Spice programs that have a graphical front
end and back end. This means we can enter the schematic, check
the viability of the models, tell it to run the included Spice 3F5
or whatever, engine, and display the results in graphical plots.
Some of these are available in free versions that are sufficiently
powerful to run your simple circuit. For example, the Intusoft
Spice CD or download that's available free at On Semiconductor.
http://www.onsemi.com/site/content/0,4367,1270,00.html
http://www.intusoft.com/ONSemiconductor.htm

But it's not hard to simply use the free spice engine by itself
and enter your spice program by hand. You must already have the
syntax manual for standard spice. If not, it's easy to find.

Number the nodes of your circuit and type in the drawing, line
by line for each component's connections. The only thing you'll
be missing is an opamp model. A number of possibilities are open
to you. Such as, pick some common opamp, and get its model from
the manufacturer's website. It'll probably be a variant of the
Boyle model. Study the model to see how it works, and modify it
for the specs of your problem.

For simple problems I sometimes like to make a basic opamp from
a VCCS and a VCVS with a capacitor to ground between them to
create the opamp's gain rolloff, plus a series output resistor...
it's worth playing with anyway. Go, and simulate your day away.
And of course you can come back to us with more questions.

--
Thanks,
- Win

Jim Thompson · Mar 21, 2005

On Mon, 21 Mar 2005 10:29:54 +0100, jeko <a.napoleoni@fastwebnet.it>
wrote:

Jim Thompson ha scritto:
On Sun, 20 Mar 2005 19:24:24 +0100, jeko <a.napoleoni@fastwebnet.it
wrote:

I must use SPICE 3f5 Berkeley version on linux system.
this is the link of my schematic design
http://tinypic.com/2aeyo0

thanx

Andrea

[snip]

Your schematic design has no values for the components. What
frequency response is it to have?

...Jim Thompson

"..The opamp model has an open loop gain of 10000.the output voltage
restriction is -1.5V +1.5V and the maximum output current is 80mA. Due
to these restrictions the whole system is nonlinear. This circuit has
two state variables, namely the capacitor voltages Vc1 and Vc2. Using
acharge oriented capacitor model willnormally lead to the two charges as
state variables. We changed this, because we found it more convenientto
think in voltages than in charges.The corner frequency Wc and the
damping factor d ar given by Wc = (Sqrt(R1*R2*C1*C2))^-1 and d =
0.5C1Wc(R1+R2). We use two different value sets for the resistors and
capacitors, one with Wc =100s^-1 and d = 0.5 and the second one at the
same frequency but with d = 2.Tus, we get twoequivalent lowpass filters
differing only by the damping factor.
The property to be checked in this example is the occurrence of
overschooting in the two filters. Since these properties should be
proved for arbitrary input signals, the appropriate input value model si
chosen. The input signal range is Vin =[-2..2] so that the nonliearity
due to the restricted output voltage will effect the system beahviour.
The state space is restricted to Vc1=[-4..4] and Vc2[-2.5 .. 2.5].Vin
start from 0."
Obviously I will change manually the variables values that I have writen
above
Thanx
Andrea

Too much classroom, and not enough thinking process ;-)

You can, indeed, parameterize component values. But you must then
declare them, and possibly sweep them from the simulator.

The schematic you have shown IS a LINEAR low pass filter, UNLESS over
driven.

Are you a PhD candidate ?

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

jeko · Mar 21, 2005

Mike Monett ha scritto:

jeko wrote:

Mike Monett ha scritto:

jeko wrote:

I must use SPICE 3f5 Berkeley version on linux system.
this is the link of my schematic design
http://tinypic.com/2aeyo0

thanx

Andrea

I believe LTSpice runs under WINE. You can get it here along with SPICE
models:

http://www.linear.com/company/software.jsp

Regards,

Mike Monett

Thank you, but I'm obliged to use only SPICE 3f5 (3f2 or higher) on
linux system.
A.

Wine runs under Linux:

http://www.winehq.com/

Mike Monett

I know, but I must use Spice...

Mike Monett · Mar 21, 2005

jeko wrote:

Mike Monett ha scritto:
jeko wrote:

Mike Monett ha scritto:

jeko wrote:

I must use SPICE 3f5 Berkeley version on linux system.
this is the link of my schematic design
http://tinypic.com/2aeyo0

thanx

Andrea

I believe LTSpice runs under WINE. You can get it here along with SPICE
models:

http://www.linear.com/company/software.jsp

Regards,

Mike Monett

Thank you, but I'm obliged to use only SPICE 3f5 (3f2 or higher) on
linux system.
A.

Wine runs under Linux:

http://www.winehq.com/

Mike Monett

I know, but I must use Spice...

LTSpice is SPICE.

It runs under Wine.

Wine runs under Linux.

Therefore, LTSpice runs in Linux.

LTSpice is a very good SPICE program. You can run it in Linux. See above.

Mike Monett

jeko · Mar 21, 2005

Mike Monett ha scritto:

jeko wrote:

Mike Monett ha scritto:

jeko wrote:

Mike Monett ha scritto:

jeko wrote:

I must use SPICE 3f5 Berkeley version on linux system.
this is the link of my schematic design
http://tinypic.com/2aeyo0

thanx

Andrea

I believe LTSpice runs under WINE. You can get it here along with SPICE
models:

http://www.linear.com/company/software.jsp

Regards,

Mike Monett

Thank you, but I'm obliged to use only SPICE 3f5 (3f2 or higher) on
linux system.
A.

Wine runs under Linux:

http://www.winehq.com/

Mike Monett

I know, but I must use Spice...

LTSpice is SPICE.

It runs under Wine.

Wine runs under Linux.

Therefore, LTSpice runs in Linux.

LTSpice is a very good SPICE program. You can run it in Linux. See above.

Mike Monett

Yes, but I can't use wine because I must open source program and I must
throw SPICE by fork system call

jeko · Mar 22, 2005

Jim Thompson ha scritto:

On Mon, 21 Mar 2005 10:29:54 +0100, jeko <a.napoleoni@fastwebnet.it
wrote:

Jim Thompson ha scritto:

On Sun, 20 Mar 2005 19:24:24 +0100, jeko <a.napoleoni@fastwebnet.it
wrote:

I must use SPICE 3f5 Berkeley version on linux system.
this is the link of my schematic design
http://tinypic.com/2aeyo0

thanx

Andrea

[snip]

Your schematic design has no values for the components. What
frequency response is it to have?

...Jim Thompson

"..The opamp model has an open loop gain of 10000.the output voltage
restriction is -1.5V +1.5V and the maximum output current is 80mA. Due
to these restrictions the whole system is nonlinear. This circuit has
two state variables, namely the capacitor voltages Vc1 and Vc2. Using
acharge oriented capacitor model willnormally lead to the two charges as
state variables. We changed this, because we found it more convenientto
think in voltages than in charges.The corner frequency Wc and the
damping factor d ar given by Wc = (Sqrt(R1*R2*C1*C2))^-1 and d =
0.5C1Wc(R1+R2). We use two different value sets for the resistors and
capacitors, one with Wc =100s^-1 and d = 0.5 and the second one at the
same frequency but with d = 2.Tus, we get twoequivalent lowpass filters
differing only by the damping factor.
The property to be checked in this example is the occurrence of
overschooting in the two filters. Since these properties should be
proved for arbitrary input signals, the appropriate input value model si
chosen. The input signal range is Vin =[-2..2] so that the nonliearity
due to the restricted output voltage will effect the system beahviour.
The state space is restricted to Vc1=[-4..4] and Vc2[-2.5 .. 2.5].Vin
start from 0."
Obviously I will change manually the variables values that I have writen
above
Thanx
Andrea

Too much classroom, and not enough thinking process ;-)

You can, indeed, parameterize component values. But you must then
declare them, and possibly sweep them from the simulator.

The schematic you have shown IS a LINEAR low pass filter, UNLESS over
driven.

Are you a PhD candidate ?

...Jim Thompson

No, I'm making my Computer Science degree thesis (specialist).I'm
italian graduand

Fred Bloggs · Mar 22, 2005

Winfield Hill wrote:

jeko wrote...

Mike Monett ha scritto:

jeko wrote:

I must use SPICE 3f5 Berkeley version on linux system.

Thank you, but I'm obliged to use only SPICE 3f5 (3f2 or higher)
on linux system.

Most of us like to use Spice programs that have a graphical front
end and back end. This means we can enter the schematic, check
the viability of the models, tell it to run the included Spice 3F5
or whatever, engine, and display the results in graphical plots.
Some of these are available in free versions that are sufficiently
powerful to run your simple circuit. For example, the Intusoft
Spice CD or download that's available free at On Semiconductor.
http://www.onsemi.com/site/content/0,4367,1270,00.html
http://www.intusoft.com/ONSemiconductor.htm

But it's not hard to simply use the free spice engine by itself
and enter your spice program by hand. You must already have the
syntax manual for standard spice. If not, it's easy to find.

Number the nodes of your circuit and type in the drawing, line
by line for each component's connections. The only thing you'll
be missing is an opamp model. A number of possibilities are open
to you. Such as, pick some common opamp, and get its model from
the manufacturer's website. It'll probably be a variant of the
Boyle model. Study the model to see how it works, and modify it
for the specs of your problem.

For simple problems I sometimes like to make a basic opamp from
a VCCS and a VCVS with a capacitor to ground between them to
create the opamp's gain rolloff, plus a series output resistor...
it's worth playing with anyway. Go, and simulate your day away.
And of course you can come back to us with more questions.

It's not a SPICE simulation that's needed- the problem statement is
state-space analysis and system trajectory in a bounded region. The
whole circuit thing is a red-herring where outputs are just artificially
clamped at boundaries such as 80ma maximum output current and OA output
restricted to +/-1.5V with simple circuit equations defining variable
trajectories in the linear unbounded region, ideal opamp behavior
assumed. Andrea needs to check out the student edition of MatLab.

Jim Thompson · Mar 22, 2005

On Tue, 22 Mar 2005 11:03:54 +0100, jeko <a@a.it> wrote:

Jim Thompson ha scritto:
On Mon, 21 Mar 2005 10:29:54 +0100, jeko <a.napoleoni@fastwebnet.it
wrote:

Jim Thompson ha scritto:

On Sun, 20 Mar 2005 19:24:24 +0100, jeko <a.napoleoni@fastwebnet.it
wrote:

I must use SPICE 3f5 Berkeley version on linux system.
this is the link of my schematic design
http://tinypic.com/2aeyo0

thanx

Andrea

[snip]

Your schematic design has no values for the components. What
frequency response is it to have?

...Jim Thompson

"..The opamp model has an open loop gain of 10000.the output voltage
restriction is -1.5V +1.5V and the maximum output current is 80mA. Due
to these restrictions the whole system is nonlinear. This circuit has
two state variables, namely the capacitor voltages Vc1 and Vc2. Using
acharge oriented capacitor model willnormally lead to the two charges as
state variables. We changed this, because we found it more convenientto
think in voltages than in charges.The corner frequency Wc and the
damping factor d ar given by Wc = (Sqrt(R1*R2*C1*C2))^-1 and d =
0.5C1Wc(R1+R2). We use two different value sets for the resistors and
capacitors, one with Wc =100s^-1 and d = 0.5 and the second one at the
same frequency but with d = 2.Tus, we get twoequivalent lowpass filters
differing only by the damping factor.
The property to be checked in this example is the occurrence of
overschooting in the two filters. Since these properties should be
proved for arbitrary input signals, the appropriate input value model si
chosen. The input signal range is Vin =[-2..2] so that the nonliearity
due to the restricted output voltage will effect the system beahviour.
The state space is restricted to Vc1=[-4..4] and Vc2[-2.5 .. 2.5].Vin
start from 0."
Obviously I will change manually the variables values that I have writen
above
Thanx
Andrea

Too much classroom, and not enough thinking process ;-)

You can, indeed, parameterize component values. But you must then
declare them, and possibly sweep them from the simulator.

The schematic you have shown IS a LINEAR low pass filter, UNLESS over
driven.

Are you a PhD candidate ?

...Jim Thompson

No, I'm making my Computer Science degree thesis (specialist).I'm
italian graduand

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

Mike Monett · Mar 21, 2005

jeko wrote:

Mike Monett ha scritto:
jeko wrote:

I must use SPICE 3f5 Berkeley version on linux system.
this is the link of my schematic design
http://tinypic.com/2aeyo0

thanx

Andrea

I believe LTSpice runs under WINE. You can get it here along with SPICE
models:

http://www.linear.com/company/software.jsp

Regards,

Mike Monett

Thank you, but I'm obliged to use only SPICE 3f5 (3f2 or higher) on
linux system.
A.

Wine runs under Linux:

http://www.winehq.com/

Mike Monett

jeko · Mar 21, 2005

jeko ha scritto:

Mike Monett ha scritto:

jeko wrote:

Mike Monett ha scritto:

jeko wrote:

Mike Monett ha scritto:

jeko wrote:

I must use SPICE 3f5 Berkeley version on linux system.
this is the link of my schematic design
http://tinypic.com/2aeyo0

thanx

Andrea

I believe LTSpice runs under WINE. You can get it here along with
SPICE
models:

http://www.linear.com/company/software.jsp

Regards,

Mike Monett

Thank you, but I'm obliged to use only SPICE 3f5 (3f2 or higher) on
linux system.
A.

Wine runs under Linux:

http://www.winehq.com/

Mike Monett

I know, but I must use Spice...

LTSpice is SPICE.
It runs under Wine.
Wine runs under Linux.
Therefore, LTSpice runs in Linux.
LTSpice is a very good SPICE program. You can run it in Linux. See above.

Mike Monett

Yes, but I can't use wine because I must open source program and I must
throw SPICE by fork system call

I have downloaded LTSpice and I'm using it under windows. It's
cool...but I can't use source code

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