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Fit schematic Answer:
The "F6" key will fit the schematic to the schematic
window. Be aware that if there has been text placed outside the schematic
this could make the overall size of the schematic small in order to
accommodate the circuit and text. |
Window
size Answer:
Yes; in any of these applications under the "Options"
menu, select "save preferences" when you've decided on a
window size and position. This information is saved indefinitely until
you decide to "save preferences" another time. |
Subdrawings
of different configurations Answer:
When you create a subdrawing using the Make Subdrawing dialog,
the "Drawing configuration to use" is specified. If you
want to make two different subdrawings from two different configurations
of the same drawing, you will have to give them different names. Then,
you can place one of them on the main drawing, run a simulation, replace
it with the other one, and rerun the simulation. However, you cannot
directly change an existing subdrawing, to base it on a different
configuration of the drawing that was used to create it |
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Build
Op-amps Answer:
First, you can bring either a generic model, or specific model using
the Parts Browser (X key). Click on the "Edit Model" box.
From there, dialog comes to view that allows you to change any of
the internal parameters of the device and save the part as a modified
"clone" of the original. Of course, new active devices can
be imported from the web and an existing or new graphic symbol can
be attached to such parts. |
Finding
a part Answer:
Simply press the "Find" box in the parts browser. Then
type in the part number (or partial data) you're interested in, and
the parts browser will automatically find it if available. |
AC
Analysis on Behavioral Models Answer:
AC Analysis uses linearization. There is no way one can correctly
multiply or divide anything during AC simulation because of the derivatives
in SPICE. As far back as ICAPS Version 7.6 (i.e., using the divider
behavioral model) you would get something that would appear reasonable,
but only if the divider was placed at the end of the circuit, and
wasn't hooked to anything else. There would be no way the divider
model results could correctly propagate to anything else while the
simulator is running.
Instead of using a divider, then a test point at the end, you can
connect two test points, (i.e., called vtop and vbottom - call or
email Intusoft tech support for the "divider_problem.DWG file).
Now run an IsSpice4 simulation and bring up IntuScope. Go back to
the schematic, right mouse click on the Scope5 text block, and choose
send script. This should plot the correct results, since the post
processor is not being used. The math is consequently done on the
end result, NOT while the simulator is running. The script will work
for any circuit as long as you place two test points called vtop and
vbottom, modify the setylimits to reasonable values, and remove newplot
commands if you want both waveforms to appear together.
If all you desire is to get the ratio of two AC signals at the end
of the simulation, then just use the example script below. Of course
the result can't be used as an input to anything else since it is
only run after the simulation is completed.
Scope5
newplot phase_graph
phase = phaseextend(phase(VTOP)-phase(VBOTTOM))
plot phase
setylimits 0 50
newplot gain_graph
gain = mag(VTOP)/mag(VBOTTOM)
plot gain
setylimits 1 1.25 |
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Pause
simulation Answer:
There's quite a bit that can be done regarding this need. If the
simulation is run for the first time, simply depress the "Esc"
key on the keyboard to pause the simulation any time during the
first simulation run. This is not necessary during successive runs.
Press "Ctrl T" on the keyboard to rescale the progressive
thumbnail waveforms. Though you cannot initially resume the simulation
once the Esc key is pressed, you can: 1) restart the simulation
by pressing the "Start" box in the Simulation Control
dialog box. 2) Then you can select "Pause" and "Resume"
from inside the Simulation Control dialog box for any successive
runs. Of course once an initial simulation run is complete, successive
runs enable the "pause" and "resume" functions
automatically without having to press the Esc. Key.
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Record
electrical measurements Answer:
After a simulation is run, bring to view the "Simulation
Control" Dialog box (via icon, or "Actions" menu, then
select "ICAPS" or "Simulation Control"). Under
the "Measurements" tab, select whatever simulation you desire
beneath its assigned simulation configuration (e.g., Setup1, AC).
Next, select the "Add" box to the right. Press the "Next"
box for the next two dialog boxes that come to view. Finally, select
whatever measurements you desire across the design and press the "Finish"
box. Of course, many other things can be specified for recording measurements
from these dialogs, but this example will furnish the most basic capability.
Re-simulate the design by pressing "Simulate Selections"
back in the "Main" tab. Press the "Results" box
once the simulation is complete. On the far left of the dialog box
that comes to view, left-click the measurement type you originally
specified and corresponding data will come to view for all selected
design nodes and components. |
Component
stress Answer:
Yes. Follow the above procedure (Record electrical measurements.)
To modify a component's electrical limits, select the test group for
the type of analysis specified: e.g., TRAN…InitialValue. Select
the expansion "+" symbol and all the components and their
current or power measurement you selected will appear (ex: @Q3[p],
meaning power through transistor 3). Select the "Edit Tol"
box to the right and examine or change the limit values for desired
components. Following the above procedure (Record electrical measurements)
will produce an electrical violation report/readout for all components
you've selected, then select desired components for monitoring out
of spec limits. |
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Auto
waveform update from IsSpice4 to Scope Answer:
Invoke
a component "Expression" dialog box (i.e., resistance,
Resistance) from the IsSpice4 window, or, a component "Stimulus"
dialog box. For an Expression: Type in the analysis parameters (i.e.,
tran 1n 100n) below the "alter" expression seen in the
dialog, then below that type in the analysis parameters again, then
below that type "sendscript update." When you press the
"Set" box, the new updated waveform will appear in IntuScope.
For a "Stimulus" dialog: Type the same above lines in
the Simulation Control window's script area (blank space toward
its bottom). This includes the Alter statement. Bring up your desired
component stimulus (i.e., resistance, Resistance) dialog box. Then,
after you vary the expression amount (i.e., by pressing the arrow
keys or assigning a numeric value), select the "Do Script"
box in the Simulation Control Window. Again, the waveform will be
automatically updated in IntuScope. Note: this is not a normal mode
for IsSpice4 and it's often best to simply perform "Alter"
in SpiceNet for quickly running component sweeps in IntuScope, or
using Simulation Control's "Expression" or "Stimulus"
functions as mentioned, but viewing the thumbnail waveforms. Ctrl
T will rescale the thumbnail waveforms.
| Example
for an Expression: |
Type
below the alter statement in the Control Vector dialog box: |
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Tran
10n 100n (or whatever the simulation is).
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Tran
10n 100n (yes, type it again)
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sendscript update (make sure you use lower case for these
3 lines)
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Verification
Analyses Answer:
No, but there is a shortcut by simply selecting the "Edit
Part" box inside the Sweep dialog and it will automatically take
you to the Part Properties dialog to fill in the sweep variable names.
Also note that once there, toward the lower right side of the dialog
from the Tolerance/Sweep/Optimize tab, lies a "No Sweep"
check box. Check this if more than 2 parts are enabled for sweeping.
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Cursor
display Answer:
Cursors are not displayed in this case because they only operate
with respect to the default X-axis values. However, you can achieve
the requested objective by simulating a design, then, for example,
make a plot of Vout vs. Time. Then make a separate plot of two different
variables such as Icc vs. V(R1). On the fist plot of Vout vs. Time,
right click on the trace and select "Link Master Trace."
On the second plot, right click and select "Auto Label Cursor
0." The value of both Icc and V(R1) will numerically appear on
this graph, with respect to the corresponding time point from the
first graph. Now, anywhere you drag Cursor 0 on the Vout vs. Time
plot, the corresponding Icc and V(R1) values will automatically be
updated. |
Background
colors Answer:
All font colors can be changed by using the "Options"
menu, then "Fonts" to change any font color within IntuScope.
Axis and background colors can be changed by selecting the "Options"
menu, then "Grid Characteristics." |
Updating
Waveforms Answer:
There are three modes to automatically update previously viewed
waveforms. Select the "Actions" menu in IntuScope, then
"Update." You'll see three update modes from which you can
choose. "Update Current Document" overwrites the existing
waveforms displayed with new data. "Add Updated Traces"
add new previously viewed waveform data to the existing plot, thus
also preserving the old traces. "Add Updated Document" brings
over the new waveform data into an entirely new waveform graph, thus
preserving the previously viewed graph. Once you've selected a desired
update mode, then simply press the <Ctrl U> keys to automatically
invoke a new waveform update. Often, an engineer will make changes
to a schematic, re-simulate, then perform a <Ctrl U> to quickly
see how desired waveforms in the design have changed. |
Circular
mils to centimeters squared Answer:
Multiply circular mils by 5.067 x 10-6 |
Area
to linear measurement Answer:
Area
always varies in direct proportion to the square of the linear dimension.
Thus, if wire A is twice the diameter of wire B, then wire A has four
times the cross-sectional area (in circular mils) of B. If wire C
is 1/5 of the diameter of wire D, then C has 1/25 the cross-sectional
area, in circular mils, of D. |
Assigning
more than one winding per layer Answer:
Having more than
one winding (including incomplete windings) on a layer invalidates
the leakage inductance and interwinding capacitance, as well as proximity
loss calculations. Mathematically the problem becomes intractable
unless an FEA tool is used. The complexity in terms of price and man
hours using FEA tools exceeds the cost of trial and error in prototyping. |
Calculating
leakage inductance between windings Answer:
Briefly, the MD
model calculates leakage between adjacent windings. It assumes no
fringing or leakage to other windings. This is part of the reason
why windings can't occupy the same layer, and why layers should be
full. To measure leakage inductance, you can short one winding and
measure the leakage inductance of its adjacent winding(s). That should
be the number obtained for the "leakage to next winding"
entry. Short circuit measurement of leakage inductance is not strictly
correct, but it's good enough for tightly coupled windings. If the
windings have the same number of turns, connect them is series-opposition
and measure leakage inductance directly - that's the true value. When
winding are split, Magnetics Designer considers each split section
separately; the equivalent circuit does not yield a simple leakage
inductance model for the combined winding. Leakage inductance is calculated
based on the uncoupled fields between the windings, so that insulation
thickness (wire plus tape) has a dramatic effect. If you break the
Magnetics Designer rules, a transformer may still be OK, but you will
need FEA software, a prototype, or attempt to calculate the leakage
field by hand. Magnetics Designer also calculates leakage between
sector wound coils, but the geometry is a bit more difficult and accuracy
for high leakage coils could be compromised. |
Can
you inflict for example a 1mv AC ripple on top of an input signal
source Answer:
Yes, use a “SUM2” component from the parts browser and assign
in its “Subcircuit Properties” dialog (by double clicking
on the part) a value of 1 to the K1 and K2 parameters. Then use 2
voltage sources as input to the
summer device, the respective sources set up for the square wave and
AC ripple.
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Different
schematic layers put into different pages Answer:
Yes,
by group copy/pasting the layer’s devices and wires into another
page. As an aside, different versions of the schematic can be saved
by creating different schematic configurations. When the schematic
configuration edit
dialog is invoked to do this, the engineer can automatically select
any of the design’s schematic layer(s) to be included the new
drawing configuration.
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Can
you set certain components' tolerances to one value for one type
of analysis Answer:
Yes,
each of the devices’ tolerances would be assigned in their
part properties dialog (T/S/O tab atop of the dialog) to the desired
amount (i.e., 2%). Note that inside that dialog’s T/S/O tab
there’s a check box
for “Apply Tolerance to all Similar Parts,” which when
checked, will set all (i.e., resistors) to the new assigned tolerance.
Once done, a desired simulation setup (i.e., transient analysis)
would be setup for that run.
Then the environment would be saved as a design configuration for
this schematic version with the new part tolerances, and the same
would be done to save this simulation setup using the “simulation
setup” dialog.
Next, the process
would be repeated for the next set of parameters for the devices
and type of simulation (i.e., 5% to the devices and say an AC analysis).
As a result, a new circuit configuration would be assigned to
this version of the design, and a new simulation setup assigned
for the AC analysis. At that point, from SpiceNet’s top toolbar,
with a mouse click, any of these design configurations and simulation
setups can be selected and run. Now, to further automate this process,
once the design configs and simulation setups have been named/saved,
you can select SpiceNet’s “Simulation Control” dialog.
Under the “Test Configuration” tab, the two types of configs
and setups can be selected and assigned unique combinations (i.e.,
transient with the 2% design config, and AC simulation with the
5% design config), which when done, brings those combinations to
the “Test Configuration” box under the “Main”
tab. Once that’s done, you can click on any of these assigned
test configurations and press “Simulate.” Or, more automated,
you can hold down the Shift key and select the test
configurations (i.e., both) and they will be simulated sequentially
and automatically!
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What
are "Lots" in Monte Carlo analysis Answer:
When assigning the amount of statistical runs in SpiceNet’s
“Simulation Control” dialog, i.e., using the “Monte”
box toward the bottom of the dialog, “Lots” refers to
the amount of times a set of statistical runs will be performed.
For instance, Lot of 3 and Cases of 5 means 5 statistical runs will
be performed 3 separate times (resulting in a total of 15 runs).
If a percentage is assigned for “Lot” in any component’s
“Parts Properties” dialog’s
T/S/O tab, then any “Lot” of runs from Monte Carlo simulation
will vary the component’s range of values away from the tolerance
mean, additionally by that Lot% amount. Typically in the Monte dialog,
Lot is assigned 1 and Cases is assigned the amount of statistical
runs desired. Lot is assigned a number other than 1 when the engineer
desires to mimic global types of changes as encountered in production,
such as boards running at different temperature, boards with tighter
tolerances on components for mil standard, etc.
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.IC
initial conditions for a transient simulation, verses using the NODESET
command Answer:
The NODESET command will let the simulator try to adjust DC conditions
as an iterative process around the Nodeset value(s) prescribed, i.e.,
for trying to establish a workable DC convergence for the Nodeset
values. Whereas assigning .IC values to nodes will force them to that
value and the simulator will only use those values. There’s advantages
to using both commands for the appropriate purpose.
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measure
delta Y-axis data Answer:
Yes; Select one waveform. Move a waveform cursor on to a point
of interest on that waveform. Move a second cursor in the same fashion
but to a point of interest on the second waveform. Next left-mouse
hold inside the second cursor's small red box and drag the box to
the actual point of interest on the second waveform. Release the
mouse and read the Delta Y data toward the bottom of the IntuScope
window.
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What
convergence options will help a design with difficult design parameters
Answer:
Use the convergence wizard accessed from the "Simulation
Setup" dialog. In
other cases these parameters have helped.
With a current design these were used:
.OPTIONS itl1=1000 abstol=1n vntol=10u.
In a current-sharing op-amp closed loop feedback design these were
used:
.OPTIONS itl1=1000 gmin=1E-9 vsectol=1E-6 acct Bypass=0
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How
can I measure a skew using the cursors in IntuScope Answer:
You can place cursor 0 and cursor 1 on different waveforms as long
as they are of the same units and are in the same plot. Just drag
and drop cursors onto different waveforms and look at the delta x
and y values. Click and hold mouse button inside the red cursor box
and move the mouse up or down. Notice that the mouse cursor turns
into an up and down arrow and that you are moving a short horizontal
black line up or down along a red vertical dashed line. Once the short
horizontal black line is above another waveform, you can let go of
the mouse button. Now you can move the cursor along this waveform.
Say all of your waveforms are in volts. Place cursor 0 on one waveform
and cursor 1 onto another. Move your 2 cursors so you get delta y=0
and delta x= to your skew value.
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