Re: plotting gm_over_Id vs IC for MOS transistor
Hello, this is a very good thread I am trying to learn from.
However the links in the post are non functioning. Is there a way to know where are they now?
Thanks.
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Re: Oscillator based on a multiple-feedback filter
That's the one. Thanks, Tony.
On 2025-04-13 14:50, Tony Casey via
groups.io wrote:
You might be referring to: MFB_Oscillator.zip.
It came up in discussions here recently, but I originally uploaded
it in 2022. Please use it as a basis rather than a blueprint.
--
Regards,
Tony
On 13/04/2025 15:38, John Woodgate
via groups.io wrote:
Did
someone upload such a circuit earlier this year? I saved,
wherever it came from, but now I can't find it.
--
Best wishes John Woodgate RAYLEIGH Essex OOO-Own Opinions Only
If something is true: * as far as we know - it's science *for
certain - it's mathematics *unquestionably - it's religion
|
Re: AC Analysis - show Mag in dBuV versus Freuqncy
Add a voltage dependent voltage source to the output node and multiply it by 1meg.?
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Re: Oscillator based on a multiple-feedback filter
You might be referring to: MFB_Oscillator.zip.
It came up in discussions here recently, but I originally uploaded
it in 2022. Please use it as a basis rather than a blueprint.
--
Regards,
Tony
On 13/04/2025 15:38, John Woodgate via
groups.io wrote:
toggle quoted message
Show quoted text
Did
someone upload such a circuit earlier this year? I saved, wherever
it came from, but now I can't find it.
|
Oscillator based on a multiple-feedback filter
Did someone upload such a circuit earlier this
year? I saved, wherever it came from, but now I can't find it.
--
Best wishes John Woodgate RAYLEIGH Essex OOO-Own Opinions Only
If something is true: * as far as we know - it's science *for
certain - it's mathematics *unquestionably - it's religion
|
Re: AC Analysis - show Mag in dBuV versus Freuqncy
Modify your source for an amplitude of 1u.All measurements will be referred to 1uV.
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Re: AC Analysis - show Mag in dBuV versus Freuqncy
1. If you are only concerned with the response
well below 1MHz, there is not much point in sweeping up to
10MHz.
2. You can't change the axis labels to dB?V
within LTspice, but you can add text to the plot pane: 0dB =
1?V. With Windows, you can get ? with ALT+0181 on the numerical
keypad, with NumLock enabled.
3. To see the effects of even small stray
inductances, put 100nH in series with each capacitor. 24 dB gain
at about 10 kHz, but see below about input impedance.
4. The input impedance [1V/I(L1)] is very low,
less than 1 ohm up to 300 kHz and a minimum of 2 milliohms at
about 10 kHz.
On 2025-04-13 02:10, Ray. Koo via
groups.io wrote:
Hi
John,
Thanks
for your response.
fc
of the first LC is 11.25kHz and that of the second?one is
32.83kHz which are << 1MHz.
I intend to show dBuV?instead of dB on the
vertical axis of the Bode plot if that is doable with LTspice.
Thanks,
Ray
Right-click on V(out) at the top of
the plot window and change it to V(out)/1u in the pane
that opens. But that is never going to work properly, or
as you expect, in practice, because those large
capacitors resonate with internal and lead inductances,
probably well below 1 MHz.
On 2025-04-12 22:07, Ray. Koo via wrote:
Hi LTspice Group,
?
I have simulated a filter which is a cascaded of two
LC low-pass filters.
I get the Bode plot Magnitude in dB versus frequency and
phase versus frequency.
?
However, I need to display the magnitude in dBuV
versus frequency.
dB is just a value but dBuV is a value with reference
1uV.
I tried few things but no one worked.
Is there a way to show dBuV vs Frequency?
Has anyone tried it before?
?
LCLC filter is uploaded.
?
Comments are appreciated!
Ray
--
Best wishes John Woodgate RAYLEIGH Essex OOO-Own Opinions
Only If something
is true: * as far as we know - it's science *for certain -
it's mathematics *unquestionably - it's religion
--
Best wishes John Woodgate RAYLEIGH Essex OOO-Own Opinions Only
If something is true: * as far as we know - it's science *for
certain - it's mathematics *unquestionably - it's religion
|
Re: AC Analysis - show Mag in dBuV versus Freuqncy
Hi John,
Thanks for your response. fc of the first LC is 11.25kHz and that of the second?one is 32.83kHz which are << 1MHz.
I intend to show dBuV?instead of dB on the vertical axis of the Bode plot if that is doable with LTspice.
Thanks,
Ray
Right-click on V(out) at the top of the plot
window and change it to V(out)/1u in the pane that opens. But
that is never going to work properly, or as you expect, in
practice, because those large capacitors resonate with internal
and lead inductances, probably well below 1 MHz.
On 2025-04-12 22:07, Ray. Koo via
wrote:
Hi LTspice Group,
?
I have simulated a filter which is a cascaded of two LC
low-pass filters.
I get the Bode plot Magnitude in dB versus frequency and phase
versus frequency.
?
However, I need to display the magnitude in dBuV versus
frequency.
dB is just a value but dBuV is a value with reference 1uV.
I tried few things but no one worked.
Is there a way to show dBuV vs Frequency?
Has anyone tried it before?
?
LCLC filter is uploaded.
?
Comments are appreciated!
Ray
--
Best wishes John Woodgate RAYLEIGH Essex OOO-Own Opinions Only
If something is true: * as far as we know - it's science *for
certain - it's mathematics *unquestionably - it's religion
|
Re: AC Analysis - show Mag in dBuV versus Freuqncy
Right-click on V(out) at the top of the plot
window and change it to V(out)/1u in the pane that opens. But
that is never going to work properly, or as you expect, in
practice, because those large capacitors resonate with internal
and lead inductances, probably well below 1 MHz.
On 2025-04-12 22:07, Ray. Koo via
groups.io wrote:
Hi LTspice Group,
?
I have simulated a filter which is a cascaded of two LC
low-pass filters.
I get the Bode plot Magnitude in dB versus frequency and phase
versus frequency.
?
However, I need to display the magnitude in dBuV versus
frequency.
dB is just a value but dBuV is a value with reference 1uV.
I tried few things but no one worked.
Is there a way to show dBuV vs Frequency?
Has anyone tried it before?
?
LCLC filter is uploaded.
?
Comments are appreciated!
Ray
--
Best wishes John Woodgate RAYLEIGH Essex OOO-Own Opinions Only
If something is true: * as far as we know - it's science *for
certain - it's mathematics *unquestionably - it's religion
|
Re: AC Analysis - show Mag in dBuV versus Freuqncy
Hello, Ray
? ? I know of no? other way then to just right click on the traces label and include a conversion equation in the expression box.
On Sat, Apr 12, 2025 at 5:08 PM, Ray. Koo via groups.io <raymond.koosha@...> wrote: Hi LTspice Group,
?
I have simulated a filter which is a cascaded of two LC low-pass filters.
I get the Bode plot Magnitude in dB versus frequency and phase versus frequency.
?
However, I need to display the magnitude in dBuV versus frequency.
dB is just a value but dBuV is a value with reference 1uV.
I tried few things but no one worked.
Is there a way to show dBuV vs Frequency?
Has anyone tried it before?
?
LCLC filter is uploaded.
?
Comments are appreciated!
Ray
|
AC Analysis - show Mag in dBuV versus Freuqncy
Hi LTspice Group,
?
I have simulated a filter which is a cascaded of two LC low-pass filters.
I get the Bode plot Magnitude in dB versus frequency and phase versus frequency.
?
However, I need to display the magnitude in dBuV versus frequency.
dB is just a value but dBuV is a value with reference 1uV.
I tried few things but no one worked.
Is there a way to show dBuV vs Frequency?
Has anyone tried it before?
?
LCLC filter is uploaded.
?
Comments are appreciated!
Ray
|
Re: Lateral PNP In Model of 741 Internal Architecture
is my best guess of the device . . . so far
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Re: Lateral PNP In Model of 741 Internal Architecture
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Re: mosfet parameter setting of imported spice model
john23,
?
In other words, your PMOS or PMOS4 schematic symbol is telling LTspice to do this:
- I want a P-channel MOSFET here,
- and I want it to be a type "CMOSP", as defined in that .MODEL statement,
- and I want it to have a Width of 100n,
- and I want it to have a Length of 1u.
?
It does not connect L and W to the imported SPICE model.? It is the other way around.? It "connects" the imported SPICE model to that MOSFET instance (M1 or M2) which also has the size values from L and W.
?
Of course you would not use W=100n and L=1u.? Those were just my examples to illustrate it.
?
Andy
?
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Re: mosfet parameter setting of imported spice model
On Sat, Apr 12, 2025 at 05:06 AM, john23 wrote:
Hello Andy, I notices that the spice model I imported doesnt have ant W,L parameters in it.
So when we define ?l=1u w=100n? ?parameters in the PMOS4 model,how does it know to connect the inported spice model to the W, L?
how does it know the names of L and W and to logiccaly connect the, to the imported spice model?
That is how SPICE works.
?
The .MODEL does not (or might not) have values for W and L.? But the instance of each transistor does have W and L values, which are applied to that instance of each MOSFET.
?
The imported SPICE model is identified by a name, which I illustrated in message 159780.? The MOSFET instance must be given the same name, as I explained in message 159780, and that is how that instance logically connects to the imported SPICE model with the same name. ?
Andy
?
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Re: mosfet parameter setting of imported spice model
Hello Andy, I notices that the spice model I imported doesnt have ant W,L parameters in it.
So when we define ?l=1u w=100n? ?parameters in the PMOS4 model,how does it know to connect the inported spice model to the W, L?
how does it know the names of L and W and to logiccaly connect the, to the imported spice model?
Thanks.
|
Re: Overriding a library diode's internal parameter(s)
Probably the easiest way is to use AKO.
?
Use a unique name for your experimental diode model so it does not conflict with existing models names in the LTspice native diode library or your own user library (if you have one).
?
Place this on the schematic:
?
.Model MUR460X AKO:MUR460 D (Rs=Rser)
?
where MUR460X is the unique model name.
?
Then use MUR460X as your diode symbol "Value" attribute.
Use N=Nx as the diode symbol "Spice line" attribute value.
?
Then use params on the schematic to define Nx and Rser and step them if you wish.
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Re: Overriding a library diode's internal parameter(s)
I'd love to get back to this when I am not visiting Mom.
On Fri, Apr 11, 2025 at 7:02 PM, Bell, Dave via groups.io <Dave.Bell@...> wrote:
This surprised me when I unintentionally did it:
¡°N" when used in the diode element line sets the number of effective diodes connected in series.? N=5 means this one diode in your schematic represents 5 diodes in series.? It can have fractional values
too, such as 5.31.¡°
?
Dave
?
?
On Fri, Apr 11, 2025 at 05:15 PM, Richard Andrews wrote:
This is how it should be done, but I got a warning in the log file using version 4.
Your schematic has two things wrong.? This is not how it should be done.
-
You defined a diode model with a name that already exists.? MUR460 is in standard.dio, in LTspice's diode library.? Don't try overriding a model that was already defined.? Aside from the warning, you don't know for sure which model definition it ends up using.?
Better to use a name like "MyMUR460" or "JUNK".
-
You altered the wrong "N".
As I discussed already (perhaps you missed it), the "N" that is inside a diode's .MODEL definition is not the same as the "N" that goes on the diode's element line.
"N" inside a diode's .MODEL definition is the diode's "Emission Coefficient".? It is the same "n" that is in the Shockley Ideal Diode Law, multiplied by (kT/q) and in the denominator of the exponent of "e".? Its normal value is 1.0, and
can be set a little larger, usually between 1 and 2, to indicate a "less perfect" diode.? That is its intended purpose.? Some SPICE models set N unusually low, apparently to construct a theoretical diode with much less than the normal forward voltage.
"N" when used in the diode element line sets the number of effective diodes connected in series.? N=5 means this one diode in your schematic represents 5 diodes in series.? It can have fractional values too, such as 5.31.
The two N's must never be confused!? They are two completely different things.
In this example, Dave wanted to use the "N" diode multiplier, which must be part of the diode element line and must not be inside the diode's .MODEL statement.? But "Rs" is a .MODEL parameter so it must be inside the diode's .MODEL statement.
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Re: Overriding a library diode's internal parameter(s)
This surprised me when I unintentionally did it:
¡°N" when used in the diode element line sets the number of effective diodes connected in series.? N=5 means this one diode in your schematic represents 5 diodes in series.? It can have fractional values
too, such as 5.31.¡°
?
Dave
?
toggle quoted message
Show quoted text
From: [email protected] <[email protected]>
On Behalf Of Andy I via groups.io
Sent: Friday, April 11, 2025 3:09 PM
To: [email protected]
Subject: EXTERNAL: Re: [LTspice] Overriding a library diode's internal parameter(s)
?
On Fri, Apr 11, 2025 at 05:15 PM, Richard Andrews wrote:
This is how it should be done, but I got a warning in the log file using version 4.
Your schematic has two things wrong.? This is not how it should be done.
-
You defined a diode model with a name that already exists.? MUR460 is in standard.dio, in LTspice's diode library.? Don't try overriding a model that was already defined.? Aside from the warning, you don't know for sure which model definition it ends up using.?
Better to use a name like "MyMUR460" or "JUNK".
-
You altered the wrong "N".
As I discussed already (perhaps you missed it), the "N" that is inside a diode's .MODEL definition is not the same as the "N" that goes on the diode's element line.
"N" inside a diode's .MODEL definition is the diode's "Emission Coefficient".? It is the same "n" that is in the Shockley Ideal Diode Law, multiplied by (kT/q) and in the denominator of the exponent of "e".? Its normal value is 1.0, and
can be set a little larger, usually between 1 and 2, to indicate a "less perfect" diode.? That is its intended purpose.? Some SPICE models set N unusually low, apparently to construct a theoretical diode with much less than the normal forward voltage.
"N" when used in the diode element line sets the number of effective diodes connected in series.? N=5 means this one diode in your schematic represents 5 diodes in series.? It can have fractional values too, such as 5.31.
The two N's must never be confused!? They are two completely different things.
In this example, Dave wanted to use the "N" diode multiplier, which must be part of the diode element line and must not be inside the diode's .MODEL statement.? But "Rs" is a .MODEL parameter so it must be inside the diode's .MODEL statement.
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Re: mosfet parameter setting of imported spice model
On Fri, Apr 11, 2025 at 04:57 PM, john23 wrote:
however in the 1:01:06 moment of the video ...
Wow.? I watched a few minutes of that video.? A few minutes was all I could tolerate.? Incredibly bad.
?
I often say that you should not rely on watching videos to learn anything about electronics or LTspice.? Here is proof.? An hour and a half of it.
?
Andy
?
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John Woodgate
Tony Casey
Ray. Koo
Rene
Bell, Dave