PSpice - Recent Threads

Your access to On-Demand Webinar : From Wall to Rail – Turning Rules of Thumb into Proof

Renu Vibha — Wed, 29 Jul 2026 05:50:12 GMT

Rules of thumb don't pass safety reviews; proof does.

This webinar demonstrates constraint-driven flyback design in Cadence’s Allegro X Design Platform and PSpice.

See how to verify hot-loop geometry, isolation spacing, and startup behavior before you build hardware.

For more details , check From Wall to Rail – Turning Rules of Thumb into Proof | Cadence

Modeling Schottky Diodes in PSpice – Understanding IS and N Parameters

IshaS — Tue, 28 Jul 2026 09:32:41 GMT

Schottky diodes are indispensable part of modern hardware design. Their low forward voltage drop (typically 0.2–0.45 V versus 0.6–0.7 V for a standard PN junction) and near-zero reverse recovery time make them go-to choice in high-frequency switching power supplies, RF signal detection, OR-ing circuits, and flyback clamp networks. Wherever efficiency, speed, or tight voltage headroom matters, a Schottky is usually in the signal path.

But selecting the right device is only half the job. Simulating it accurately is the other half and that's where most designs quietly go wrong.

In PSpice, a Schottky diode's behavior is governed primarily by two model parameters: IS (reverse saturation current) and N (ideality factor). These two values define the entire shape of the I-V curve. Get them right, and your simulation predicts forward voltage drop, power dissipation, and switching behavior with confidence. Get them wrong - which happens whenever you use an unverified default model - and every downstream calculation built on that simulation is off including thermal margins, efficiency estimates and gate drive timing.

This post walks through how to tune IS and N in PSpice using nested DC sweeps, so your simulation matches the datasheet and holds up on the bench.

The diode current is governed by the equation:
I = IS (e^(V / (N·Vt)) − 1)

This indicates that both IS and N play an important role in determining the forward voltage characteristics.

IS (Reverse Saturation Current): Determines where along the voltage axis the I-V curve sits. In Schottky models, IS is typically several orders of magnitude larger than in standard PN junctions — often in the μA to mA range — which is the physical reason Schottky diodes conduct at a lower forward voltage. A lower IS shifts the curve to the right, increasing Vf for a given forward current. A higher IS shifts it left, reducing Vf.

N (Ideality Factor): Controls the steepness of the exponential rise. An ideal diode has N = 1; real Schottky devices typically fall between 1.0 and 2.2 depending on the junction technology and operating region. A higher N flattens the curve — you need more voltage to drive the same current — and also makes the forward voltage more sensitive to temperature variation.

Together, IS sets the operating point and N shapes the curve around it. Both need to be calibrated to the actual device for the simulation to be trustworthy.

Simulation Steps:

Perform a DC sweep analysis on a forward-biased circuit.

Use Parametric sweeps to vary IS and N independently.
Example ranges:
- IS: 3e-04 to 3e-08
- N: 2.2 to 3
Observe resulting changes in forward voltage and current characteristics.

Effect of IS (Reverse Saturation Current):

- Forward voltage drop can be tuned by modifying IS.
- A lower IS results in a higher forward voltage for the same current.

Effect of N (Ideality Factor):
- Controls the slope of the I-V curve.
- Changing N modifies exponential behavior and deviation from ideal characteristics.

This approach helps in accurately matching the diode model to real device behavior and achieving reliable simulation results.

Have you run into a Schottky (or any diode) model that just wouldn’t match the datasheet or your bench data?
Drop your experience in the comments – what device, what mismatch, and how you resolved it.

Happy Learning!!

Associate psice model greyed out

Shashank — Tue, 21 Jul 2026 16:35:43 GMT

OrCAD X Capture 24.1.
Created Project A without selecting Enable PSpice Simulation.
Created Project B with Enable PSpice Simulation selected.
Placed the same SamacSys Library Loader component in both projects.
In Project A, Associate PSpice Model is grayed out.
In Project B, Associate PSpice Model is enabled.
Since Simulation Profile can still be created in both Projects , I am unsure why only Associate PSpice Model is disabled.
Is this expected behavior in OrCAD X Capture 24.1?
Is there a supported way to enable Associate PSpice Model in an existing project created without Enable PSpice Simulation, or is creating a new PSpice-enabled project required?
Is there any project setting that controls the availability of Associate PSpice Model?

PSpice Special Components: Print1, Print2 and PRINTDGTLCHG

AyushD — Tue, 07 Jul 2026 16:41:44 GMT

Print1:

Use this component to insert .PRINT command in your simulation. This component enables you to print voltage at node in simulation output (.out) file.

You need to configure one or more parameters on this symbol instances from following list to use in simulation flow.

Analysis Type: Assign any value to one of the variables AC/DC/TRAN, depending upon the analysis you are performing. For example if your simulation profile is configured for Transient Analysis you should set TRAN property value as 1.
Functions: You can use following special function on output nodes
- DB
- PHASE
- REAL
- MAG
- IMAG
You can use one or more of the parameters at a time. To select these you need to assign any value to these parameter, say, 1. For example, if you have set DB and PHASE values to 1 on symbol instance and this component is connected to node VOUT, it will print following in output file:
DB of Voltage at VOUT node
PHASE of Voltage at VOUT node

Print2:

PRINT2 performs the same function as PRINT1, only difference being this component should be used for differential voltage between two nodes.

PRINTDGTLCHG:

Use this component for digital nodes. It lists every change of state for a given node in the output file. You need not specify any parameter on this symbol instance.

使用 PSpice-for-TI时，显示这个芯片没有在已配置的库中找到，我尝试在Simulation Settings中配置，

WZ202606154651 — Mon, 15 Jun 2026 14:22:10 GMT

使用 PSpice-for-TI时，我在我自己创建的例程中使用LMR33630ADDA_TRANS等芯片时，会出现一个警告，显示这个芯片没有在已配置的库中找到，我尝试在Simulation Settings中配置，并没有什么用，并且仿真结果异常

Exporting PSPICE netlist with Subckt parameters

SC202412036016 — Wed, 03 Jun 2026 20:44:16 GMT

I am trying to export a PSPICE netlist of a simple subcircuit where I have to pass in parameters, however parameter definition is happening after ENDS, instead of the top line where the subcircuit is being defined. There is a .PARAMS in the subckt line however the actual parameter (lval) is showing up right at the end. Any ideas on where the issues may be?

I cannot seem to attach a screenshot of the template settings, but if this works for anyone would be great if you can send a screenshot of the template settings where the ParamList is displayed at the top.

1. To extract the netlist I go to Tools > Create Netlist

2. Here is the output:

* source BLOCK_AOL
.SUBCKT Aol_Block InN InP OutN OutP PARAMS :
G_G1 OUTP OUTN INP INN -1u
L_L1 N00976 OUTN {LVAL} TC=0,0
R_R2 N00976 OUTP 1M TC=0,0
.ENDS Aol_Block
.PARAM lval=1n

Persistent netlisting error

AG202606016357 — Mon, 01 Jun 2026 12:07:33 GMT

Hello,

I'm using "PSpice for TI" to simulate a DCDC converter implementing a specific TI PWM controller (hence the selection of the simulation tool).

My schematic is drawn and seems correct. Still, when I launch the netlist generation, I get the following error message:

"ERROR(ORCAP-15065): There are netlisting errors.

Check the session log."

In the session log, I find:

"INFO(ORNET-1041): Writing PSpice Flat Netlist \\xxx\yyy\SCHEMATIC1\SCHEMATIC1.net
INFO(ORNET-1169): Unable to open the property mapping file: devparam.txt. To resolve this problem, ensure that PSpice.ini exists at the correct location. After that check Library Path in simulation settings contains <installation-path>/tools/pspice/library path and then create the netlist again.
INFO(ORNET-1162): Unable to create design property file"

I completed the proposed checks and everything is OK.

I gave a try with a very simple schematic (1 DC source, 1 ideal R and 1 ideal C). I got the exact same error.

How can I solve this error?

What should I do?

Thanks for helping me.

PSpice Special Component: Watch1

AyushD — Sun, 31 May 2026 19:15:05 GMT

.WATCH command enables user to observe voltage at node in simulation status windows while simulation is in progress.

Attach this part (WATCH1) at node or net which you will like to observe during the simulation. After this, you need to define following three parameters on symbol instance:

Analysis: Assign the one of the following three values depending upon the type of analysis being performed:
DC
AC
TRAN

HI: Assign a numeric value to define upper limit of voltage
LO: Assign a numeric value to define lower limit of voltage

Simulator pauses if voltage at node is outside of range defined by HI and LO.

Unable to Upload Images

MrTF — Mon, 04 May 2026 16:26:34 GMT

Dear all,

I have tried several times to upload an image from my simulation in order to post a question.

Unfortunately, this has not been possible so far. Each time, I receive a message advising me to contact the administrator.

Could you please let me know how to proceed or whom I should contact to resolve this issue?

Thank you in advance for your support.

Model stepping in PSpice

IshaS — Thu, 30 Apr 2026 16:38:48 GMT

Starting with SPB 25.1, PSpice introduces model stepping, which allows multiple models of the same component to be simulated in a single run and compared directly in the Probe window. All results are stored in one data file, making side‑by‑side analysis simple and efficient.

This is done using the. modelstep directive. For example, as shown in the following image, for the given circuit, a .modelstep statement has been defined as:

@PSpice:

.modelstep STPSC10065D MUR1560

Now, tool will simulate the design with both the PSpice models for D1 as defined in the above statement (STPSC10065D and MUR1560).

When the simulation is run, PSpice automatically steps through both models and displays their results together in the Probe window. This makes it easy to compare waveforms and performance and select the most suitable device. The Probe output also shows the total job time for all stepped models.

Try this and share your insights!

Happy Learning !!

Efficient Method to Perform Temperature Sensitivity Analysis and Rank Dominant Components in PSpice

MrTF — Thu, 30 Apr 2026 15:43:57 GMT

I am working on a precision analog circuit and I want to assess temperature sensitivity and identify which components dominate performance variation due to temperature in an efficient and automated way.

My objective is not simply to observe output variation of a specific performance metric versus temperature, but to:

Quantify the sensitivity of a performance metric (e.g., output current, impedance, or noise) with respect to temperature
Attribute this variation to individual components (R, L, C, coupling factors, parasitics, etc.)
Rank components based on their contribution to the overall temperature-induced variation

One approach I considered is to encode temperature effects as equivalent tolerances (i.e., mapping TC-induced drift into % variation) and then perform a standard sensitivity or worst-case analysis. However, this would require maintaining two versions of the circuit (nominal vs “temperature-perturbed”), which is not practical or scalable.

To clarify, I am not referring to a simple global temperature sweep or single-parameter variation. I am looking for a method that enables systematic decomposition of temperature effects across all components.

Is there a rigorous and efficient workflow in PSpice/Cadence to:

perform sensitivity analysis with respect to temperature and
automatically identify and rank the dominant contributors?

Any guidance on built-in features I may miss would be highly appreciated.

OP467 Component - Simulation Model Issue

MrTF — Tue, 14 Apr 2026 11:07:43 GMT

Dear all,

I am using the OP467 model, which I selected via (Menu)
Place → Component → PSpice Category Model.

During simulation, I receive the following warning:

DRC Type: Electrical
Warning (ORCAP‑2445)
Instance UxD, SCHEMATIC1, PAGE 1 (XXX.xx, XXX.xx),
not found in the configured libraries.

Could someone please clarify:

What exactly does this warning refer to?
Does it imply any potential malfunction or inaccuracy in the simulation results?
Why is the component reported as “not found in the configured libraries,” even though it appears to be located under the CIS Unified Library?
In the model I use there is a parameter with the description "LEVEL 3". To what this parameter refers to?

Any guidance would be greatly appreciated.

Thank you in advance.

Ground connection in simulating three phase PFC

GM202604016252 — Fri, 03 Apr 2026 09:50:19 GMT

Hi everyone,

I’m simulating a three‑phase PFC in ORCAD PSPice. The real circuit also includes an input LC filter, which I’ve omitted here for simplicity, but the behavior I’m seeing is always the same. In my current setup, the Pspice ground reference is connected to the negative node of the rectifier bridge, while the three AC sources have their star point left floating. During simulation, I observe that it is the star point of the generators that “moves” with respect to ground, while the negative node of the bridge remains fixed because it is tied to the reference. Which is of course normal for my simulation.

I’m wondering whether this behavior is correct. Can this simply be considered a consequence of how the simulator assigns the ground reference, or am I introducing a significant error compared to the real‑world behavior of the circuit? In other words, is it acceptable that the generators’ star point moves while the rectifier negative stays fixed, or could this lead to unrealistic results?

Another thing I don’t fully understand: if I try the opposite approach—connecting the ground to the star point of the generator and leaving the bridge negative floating (using a very large resistor like 5 MΩ instead of the direct connection)—the simulation immediately diverges, leaving me with no results. Is there a way to stabilize the simulation in this configuration, or is it inherently problematic?

My main question is: how can I simulate a circuit in which I connect the ground to the star point of the generator and leave the bridge negative floating?

My simulation profile is: time transient form 0 to 180ms, starting to save data from 160ms. this time to allow the PFC to stabilyze.

Thanks in advance to anyone who can help clarify this.

Using SMSTP(x, r) for Smoother and Faster Simulations in Allegro PSpice

IshaS — Tue, 24 Mar 2026 11:41:07 GMT

Hello everyone,

If you're using traditional step functions (like STP or Heaviside) in PSpice, you’ve probably seen issues such as sharp discontinuities, tiny timesteps, slow simulations, and convergence problems.

To overcome these limitations, Allegro PSpice introduces the SMSTP(x, r) function, which is defined as:

SMSTP(x,r)=0.5+0.5⋅tanh(r⋅x)

This gives a smooth transition from 0 → 1, and the parameter r lets you control the steepness.
Higher r = sharper but still smooth transition.

Advantages of SMSTP in Allegro PSpice:

Simulator-Friendly: It reduces the need for tiny timesteps, thus speeding up simulations.
Improved Convergence: Smooth transitions help solvers reach solutions more reliably.
Tunable Behavior: The r parameter controls the steepness and domain of the transition, as shown below:
- r = 2 transition over domain > [-1, 1]
- r = 4 domain > [-0.5, 0.5]
- Higher r values > sharper transitions within narrower domains

Hope this helps anyone working on switching or behavioral models! If needed, I can share example plots or circuit snippets.

Happy Learning!!

How to add the .net file provided by EPC for simulation

KW202603107421 — Tue, 10 Mar 2026 09:52:49 GMT

When simulating the LMG1210, I want to use real GaN switches in the simulation. However, for models like the EPC2204, the manufacturer only provides a .net file. After changing the file extension to .lib, capitalizing .subckt and .ends, and appending EPC2204A, the simulation model still cannot be read.

Exporting parts to capture library not working as expected

cabala — Tue, 03 Mar 2026 19:16:47 GMT

I am sure some variant of this question has been asked but I don't see anything quite applicable when searching the forum. I have been using OrCAD PSpice for like 15 years on and off again and I swear the process to import models, associate them with a symbol and proceed to use them in a simulation has never been improved.

We only use OrCAD for the PSpice functionality and do not create boards, etc.

What I'd really like to understand is how to replicate model libraries and capture libraries similar to the pre-packaged ones included at install (multiple models and parts per library).

Here are the steps I would think should work (but don't).

1. Open PSpice Model Editor and create a new blank library (e.g., BJTS.lib)

2. Import new model using Model -> Import and select whatever model downloaded from manufacturer, etc

3. Export to Capture library using File -> Export to Capture Part Library and associate part with a symbol

4. In Capture, add new BJTS.OLB library, choose part and add to simulation

5. Add the BJTS.lib as an include file and simulate

This works until I try to add another model. One would think you just open the model library, import new model, then re-export to capture library. Update design cache if needed or delete the capture library and re-add it. However, the only capture part ever available is the very first one I added. There are no errors during the process and when I export to capture library after adding a new model, I see all the parts in the associate symbol dialogue box. They are associated with symbols, and the event logger says everything passed with zero errors or warnings. But still, only one part in the capture library. If I repeat the process, it says there are already symbols associated with the parts. So again, it seems to be working but in Capture there is only one part shown in the olb.

I really don't understand what I am doing wrong here. I can create an individual library for each part and that works but I'd really like to make an all-in-one library for various part types that can be shared with colleagues.

Any advice or corrections would be greatly appreciated. Thanks!

Has anyone simulated the AMC3301?

deanv — Wed, 25 Feb 2026 06:27:52 GMT

I have followed the data sheet examples and am getting nothing but errors. I am a new PSpice for TI user. I tried using Google for help. It did help find a few mistakes but overall, it did not help. Is there a reference design that uses this part?

LMR51625Y Buck converter simulation Too slow

SS202602185019 — Wed, 18 Feb 2026 17:27:02 GMT

"Hey, I’m running a simulation with the attached circuit and config, but it’s running incredibly slow. I’ve set the Run To Time to 50ms with a Maximum Step Size of 100ns. That’s 500,000 steps minimum, and it's taking forever. Does the step size need to be this granular, or is there something in the circuit causing a convergence bottleneck?" , This simulation is after 5 Minutes

Hi Pspice team, I am getting the follwoing error even after configuration files added.

SK202602095340 — Mon, 09 Feb 2026 12:23:50 GMT

How to fix this error.

INFO(ORCAP-2191): Creating PSpice Netlist
INFO(ORNET-1041): Writing PSpice Flat Netlist c:\cadence\spb_23.1\tools\pspice\user_lib\lm741-pspicefiles\lm741_test-PSpiceFiles\SCHEMATIC1\SCHEMATIC1.net
INFO(ORNET-1169): Unable to open the property mapping file: C:\Cadence\SPB_23.1\tools\PSpice\Librarydevparam.txt. To resolve this problem, ensure that PSpice.ini exists at the correct location. After that check Library Path in simulation settings contains <installation-path>/tools/pspice/library path and then create the netlist again.
INFO(ORNET-1162): Unable to create design property file.

GLAPLACE XFORM Syntax Recommendation

cabala — Wed, 04 Feb 2026 17:28:50 GMT

Hi all, I am looking to see if anyone has a recommendation on how to enter this s-domain polynomial into the XFORM property field more compactly?

(1.76633807e-28*s*s*s*s*s*s*s + 4.37752348e-24*s*s*s*s*s*s + 2.21287946e-20*s*s*s*s*s + 1.63859923e-16*s*s*s*s + 4.51408684e-13*s*s*s + 1.45284939e-9*s*s + 1.42274997e-6*s + 1.19109226e-3) / (-2.49510738e-29*s*s*s*s*s*s*s*s + 3.28470008e-24*s*s*s*s*s*s*s + 1.36672855e-20*s*s*s*s*s*s + 2.41372502e-16*s*s*s*s*s + 6.79605490e-13*s*s*s*s + 4.23416528e-9*s*s*s + 6.15007649e-6*s*s + 6.30604299e-3*s + 1)

It's an 8th order polynomial curve fit for an impedance model. It has been tested and works.

I tried to create .PARAM statement in an include file for "num" and "den" but it didn't like the 's' variable which makes sense but the above is super cumbersome. Is there a way to define other properties and have XFORM reference that?

Thanks!

Test Your Simulation Skills !!

IshaS — Mon, 24 Nov 2025 14:32:34 GMT

Which simulation type is best for analyzing distortion and harmonics in PSpice A/D Analysis?

FFT with DC Sweep
FFT with transient analysis
FFT with AC Sweep

Share Inputs !!

How to import PSpice for TI library in Capture 24.1

GM202501062717 — Wed, 05 Nov 2025 20:39:45 GMT

Hello,

In 17.4, there used to be a very easy method to include PSpice for TI libraries and symbols in the full commercial Capture Editor. Now in 24.1, I cannot figure out how to add the PSpice for TI models into the new part search. While it is nice to be able to sync ultralibrarian and other databases, I am very frustrated that I have two installs, PSpice for TI and Capture CIS 24.1, but cannot get the models synced across simulators. I have tried importing nom_pspti.lib into my configuration files, which did not work.

Any suggestions here would be greatly appreciated. Thank you!

Gerasimos

Pspice would develop the new feature: Smith chart? or Develop the Python Interface for data analysis?

Zhuang Ma — Wed, 05 Nov 2025 05:36:15 GMT

I have a new idea: Smith chart? It refert to ABM Model study?

G-ABM model, E-ABM model. It means we have lots of analysis in the circuit

Measurement Syntax - Failing Simulation

WM202510282226 — Tue, 28 Oct 2025 13:30:23 GMT

Hello,

I am wanting to find the time at which when the difference between two voltages is less than a specified value.

My initial take (below) was this using google AI, but that doesn't work, and I find the documentation exceptionally unhelpful. At least for Orcad 17.2.

.MEAS TRAN res4 FIND time WHEN V(Vin)-V(Vb)=0.62

This looks LTspice like, so I imagine it's getting confused. I am running a monte-carlo, so I would like the command to be run each and every time there is a simulation run. So, if there are 100 runs, then there should be 100 data points of a time being given.

TI SPICE reports "File is read only or used"

FL20250929850 — Mon, 29 Sep 2025 08:53:37 GMT

I am using TI SPICE and try to run a simulation which works for the initial downloaded TI package (TL431). I can start the simulation as it it was provided by TI download.

But I can not save or change the simulation profile or schematic: Message is following

- tran is read only: can not update

- schematic is read only

In general it seems that the whole project is read only.

How can I change it from read only to editable?