1. SPICE
SPICE (simulation program with integrated circuit emphasis) is a general-purpose circuit program that simulates electronic circuits. It can perform analyses on various aspects of electronic circuits, such as the operating (or quiescent) points of transistors, time-domain response, small-signal frequency response, and so on. SPICE contains models for common circuit elements, active as well as passive, and it is capable of simulating most electronic circuits. It is a versatile program and is widely used in both industry and academic institutions.

2. PC + SPICE = PSPICE
Until recently, SPICE was available only on mainframe computers. In addition to the cost of the computer system, such a machine can be inconvenient for classroom use. In 1984, MicroSim introduced the PSpice simulator, which is similar to the Berkeley version of SPICE and runs on an IBM-PC or compatible, and is available free of cost to students for classroom use. PSpice© thus widens the scope for the integration of computer-aided circuit analysis into electronic circuits courses at the undergraduate level.

3. There are many types of PC versions of SPICE:
AllSpice (from Acotech)
Is-Spice (from Intusoft)
Z-SPICE (from Z-Tech)
SPICE-Plus (from Analog Design Tools)
DSPICE (from Daisy Systems)
PSpice (from MicroSim)
OrCAD (from Cadence)
Spice (from KEMET)
B2 Spice A/D (from Beige Bag Software)
AIM-Spice (from AIM-Software)
VisualSpice (from Island Logix)
Spice3f4 (from Kiva Design)
OrCAD SPICE (from OrCAD)
MDSPICE (from Zeland Software, Inc.)
Ivex Spice (from Ivex Design)

4. OrCAD Capture, PSpice Simulation, PCB Layout Design & Routing Software
Schematic editor
Parts library
Analog and digital simulation
Model editor
PCB designer
Autorouting
PCB manufacturing

5. Typical structure of PSpice based simulation program

6. Circuit, netlist, input file, command

7. Nodes
Node numbers are assigned by PSpice and are usually alphanumeric such as $N_0005 and $N_0003
All nodes must be connected to at least two elements
Node 0 is predefined as the ground
All nodes must have a DC path to the ground node (This condition, which is not met in all circuits, is normally satisfied by connecting very large resistors)
we can rename the nodes arbitrarily (for example – input, output)

8. What is “Design Cache”????... Go and Find Out Yourself 
Parts
Part is a basic building block which may represent
One or more physical element (diode, resistor, operational amplifier etc.)
Function (multiplication, integration, table etc.)
Simulation model (model of DC motor)
When a part is placed for first time its entry is done in “Design Cache”
What is “Design Cache”????... Go and Find Out Yourself 

9. PART VALUES
The values are written in standard floating-point notation with optional scale and units suffixes
Decimal separator is only decimal point
PSpice is case insensitive
2200 … 2.2k … 2.2K … MEG … 2.2E+3 but not in this way: 2k k
10M … 10m … 0.01 m = mili !!! meg = mega … 10meg
The first suffix is always the scale sufix, the units suffix (Volt, Amper etc.) follows the scale sufix, but PSpice ignores any units suffix, and the following values are equivalent:
25E– E–3 25M 25MA 25MV 25MOHM 25MH

10. Symbols of Circuit Parts and Sources
First Letter Circuit Parts and Sources
B GaAs MES field-effect transistor
C Capacitor
D Diode
E Voltage-controlled voltage source
F Current-controlled current source
G Voltage-controlled current source
H Current-controlled voltage source
I Independent current source
J Junction field-effect transistor
K Mutual inductors (transformer)
L Inductor
M MOS field-effect transistor
Q Bipolar junction transistor
R Resistor
S Voltage-controlled switcha
T Transmission line
V Independent voltage source
W Current-controlled switch
Z IGBT transistor

11. Models
Models are used to assign values to the various parameters of circuit elements
Each element must be characterized by at least one value (resistor, capacitor, inductor)
Some element (transistors, integrated circuits, logic gates etc.) are characterized by several values
component models are located in the appropriate libraries

12. PSpice allows four basic types of analysis:
Bias Point - calculates the DC operating point of the circuit.
Usually we examine the behaviour of a circuit while something varies. The variable might be
time (Transient Analysis),
the frequency of a signal (AC sweep) or
the magnitude of a voltage, current,
temperature or some parameter (DC sweep)

13. Bias Point
The Bias Point analysis is the starting point for all analysis
In this mode, the simulator calculates the DC operating point of the circuit
Capacitors are open circuits and inductors are shorts
Only DC supplies are applied
Analysis results are stored in the output text file
Options include calculating the detailed bias points for all nonlinear controlled sources and semiconductors, performing sensitivity analysis, and calculating the small signal DC gain

14. DC Sweep
The DC Sweep analysis varies a voltage or current source or temperature or defined parameter over a range in an assigned number of increments
Capacitors are open circuits and inductors are shorts
Only DC supplies are applied

15. AC Sweep/Noise
The AC Sweep/Noise analysis varies the operating frequency on the supplies, where is AC parameter set
PSpice linearizes the circuit around the DC operating point and then calculates the network variables as functions of frequency
The start and stop frequencies as well as the number of points can be assigned

16. Time Domain (transient)
The Time Domain (transient) analysis is probably the most popular analysis
In this mode, you can plot the various outputs as a function of time
The starting and ending times for the various plots can be input
The accuracy (smoothness) of the output plots can also be controlled by regulating the maximum (time) step size
Options include calculating the Fourier analysis

17. Getting Started Start OrCAD and select File  New  Project
Make sure to choose Analog or Mixed A/D,
name of project and proper location for project
Make sure you select “Create a blank project”

18. Schematic window project manager zoom
display of the working point V, I, W
markers
display of results of simulation
start simulation
simulation profile
design cash
active simulation profile

19. Schematic window placing components, connecting etc. part wire
node rename (net alias)
bus
junction
power pin
ground
drawing
placing components, connecting etc.

20. Place Part Selected part Active library content Add library
Remove library from list
Active library
Libraries selected for project
Schematic part
Part search
PSpice model exist
Exist case for part

21. Connecting components
Wire
Power pins (Power, Ground)
Net Alias
Nodes with the same name are automatically linked

22. Things to remember before starting
Draw a schematic as well as a real circuit
There must be a node designated "0" (Zero). This is the reference node against which all voltages are calculated
PSpice is not case sensitive
an unconnected pin usually causes an error
the value of the resistor, inductor or capacitor must not be 0
Error messages can be found in the Session Log window or in the Output File

23. OrCAD Capture
Session Log
Project Manager
Schematic Page

24. Project manager Disk file with the project Schema containing one page
Design cache
Output files
Netlist
Simulation profiles

25. Design Example Take example of a high pass filter (RC)
First we will follow initial steps of creating a new project
Now placing the components.

26. Place the components
Library ANALOG

27. Place the source and ground
Library SOURCE

28. Add Wire and Probe
Probes (markers)

29. Creating new simulation profile
Give a name to profile and create

30. AC Analysis We can choose any of the analysis and options
Here AC analysis is done to see operation of filter

31. Run
Run PSpice
Another waveform window will come up

32. Simulation Profile
The analysis setting is stored in the simulation profile
Each schema in a project may have any number of profiles associated, but only one can be active
Creating new simulation profile:

33. Simulation setup Probe settings
Setting accuracy and other simulation conditions
Data storage settings
Setting paths to external files
Select the type of analysis and its detailed settings
Information on input and output files, simulation notes

34. Probe settings Start probe Display settings:
Display all markers on schematics
Display last plot settings – settings of axes range,
number of axes, selected traces, colors etc.

35. Analysis settings - Bias Point
There is no need to set anything
The results of the analysis are stored in the Output File
The operating point data can be displayed in the schematic

36. Analysis settings - Time Domain (transient)
End time of simulation Start is always at t = 0.
Size of the maximum calculation step of the simulation (optional)

37. Analysis settings - AC Sweep/Noise
The AC Sweep/Noise analysis varies the operating frequency on the supplies, where is AC parameter set
mandatory parameters
What is decade/octave?

38. Analysis settings - DC Sweep
Voltage Source, Current Source - DC component of the voltage (current) source. The value set in the schematic is ignored
Global Parameter - Global parameter sweep. The global parameter must be declared using the PARAM pseudo-part
Model Parameter - Sweep parameters of the model - requires knowledge of the model type and the names of its parameters (this is for advanced users)

39. Chyby a jejich odstranění
Soubor s hlášením o průběhu simulace a chybách Output File
Nejčastější chyby v zadání obvodu
Floating Nodes - nezapojený uzel nebo chybí „zem“
Inductor Loops - smyčka induktoru s nulovou rezistencí
Mezi číselnou hodnotou a příponou je mezera
Logaritmický interval rozmítání obsahuje nulu
Hodnota R, L nebo C je nulová
Chybějící deklarace globálního parametru
Chyby simulace - konvergenční problémy
Zvětšení chybové tolerance ABSTOL RELTOL (absolutní a relativní přesnost výpočtu)
Připojit malé rezistory do série, nebo velké paralelně k prvkům, které jsou příčinou konvergenčních problémů
Přiřadit malou, ale konečnou hodnotu době nárůstu (TR), době poklesu (TF) a šířce pulsu (PW) u pulsního zdroje
Nastavit vhodné počáteční podmínky simulace

40. Frequently encountered errors
The errors are highlighted in the Output file
The most common errors in the input of the circuit
Floating Nodes - unconnected node or missing „ground“
Inductor Loops - inductor loop with zero resistence
There is a space between the numeric value and the suffix
The logarithmic sweep interval contains zero
The value of R, L or C is zero
Missing declaration of global parameter
2. Simulation Errors - Convergence problems
Increase the absolute and relative accuracy of the calculation
Connect small resistors in series or large parallel to the elements that cause convergence problems
Assign a small but finite value of the rise time (TR), a falling time (TF) and pulse width (PW) in a pulse source
Set appropriate initial conditions of the simulation

41. Postprocessor Probe
1, 2 or 3 y axes
Analog and digital section
x axis

42. Postprocesor Probe (detail)
marking active axis
output variable
number of Y axis of the trace
graphic symbol of the trace

43. Display simulation results
Use of measuring probes (markers)
Trace  Add Trace  Select variable

44. Display of calculated data points

45. Add Y Axis Two traces in one axis Each trace has its axis
Voltage in Volts
Current in micro-amps

46. Add Plot

47. Cursors On/Off Cursors Cursor1
Click LMB on graphical symbol of the trace
Cursor2
Click RMB on graphical symbol of the trace
X Values (time)
Y Values (Voltage)