Introduction Circuit Simulation Software and PSPICE Engine
SPICE is a powerful general purpose analog and mixed-mode circuit simulator that is used to verify
circuit designs and to predict the circuit behavior. This is of particular importance for integrated circuits.
It was for this reason that SPICE was originally developed at the Electronics Research Laboratory of the
University of California, Berkeley (1975), as its name implies: Simulation Program for Integrated Circuits
Emphasis
PSpice is a PC version of SPICE (which is currently available from OrCAD Corp. of Cadence Design
Systems, Inc.).
SPICE can do several types of circuit analyses. Here are the most important ones:
• Non-linear DC analysis: calculates the DC transfer curve.
• Non-linear transient and Fourier analysis: calculates the voltage and current as a function of time
when a large signal is applied; Fourier analysis gives the frequency spectrum.
• Linear AC Analysis: calculates the output as a function of frequency. A bode plot is generated.
• Noise analysis
• Parametric analysis
• Monte Carlo Analysis
In addition, PSpice has analog and digital libraries of standard components (such as NAND, NOR, flipflops,
MUXes, FPGA, PLDs and many more digital components, ). This makes it a useful tool for a wide
range of analog and digital applications. All analyses can be done at different temperatures. The default
temperature is 300K.
The circuit can contain the following components:
• Independent and dependent voltage and current sources
• Resistors
• Capacitors
• Inductors
• Mutual inductors
• Transmission lines
Operational amplifiers
• Switches
• Diodes
• Bipolar transistors
• MOS transistors
• JFET
• MOSFET
• Digital gates
For further details refer user manual of PSPICE
All analysis can be done in different temperatures but the default is 300K.
Some Facts and Rules about PSpice
· PSpice is not case sensitive. This means that names such as Vbus, VBUS, vbus and even vBuS are
equivalent in the program.
· All element names must be unique. Therefore, you can't have two resistors that are both
named "R1," for example.
· There must be a node designated "0." (Zero) This is the reference node against which all
voltages are calculated.
· Each node must have at least two elements attached to it.
PSpice is a computer program used mostly by engineers and scientists. Accordingly, it was created with
the ability to recognize the typical metric units for numbers. Unfortunately, PSpice cannot recognize
Greek fonts or even upper vs. lower case. Thus our usual understanding and use of the standard metric
prefixes has to be modified. For example, in everyday usage, "M" indicates "mega" (106) and "m" stands
for milli (10-3). Clearly, this would be ambiguous in PSpice, since it is not case sensitive. Thus, in PSpice,
a factor of 106 is indicated by "MEG" or "meg." "M" or "m" is reserved for 10-3. Another quirk of PSpice
is the designation for 10-6. In most publications, the Greek letter, μ, is used for this multiple. Since
there can be no Greek fonts (or any other special font designations) in PSpice, the early developers of
PSpice borrowed a trick from those who used typewriters. Before the IBM Selectric typewriter was
introduced, most writers of technical papers had to improvise for Greek letters. Since the Latin letter
"u" (at least in lower case) sort of resembled the lower case Greek μ, it was widely used as a substitute
for μ. Hence, either "U" or "u" stands for 10-6 in PSpice. Without further background explanations,
these are the metric prefix designations used in PSpice:
Number Prefix Common Name
· 1012 - "T" or "t" tera
· 109 - "G" or "g" giga
· 106 - "MEG" or "meg" mega
· 103 - "K" or "k" kilo
· 10-3 - "M" or "m" milli
· 10-6 - "U" or "u" micro
· 10-9 - "N" or "n" nano
· 10-12 - "P" or "p" pico
· 10-15 - "F" or "f" femto
An alternative to this type of notation, which is in fact, the default for PSpice output data, is "textual
scientific notation." This notation is written by typing an "E" followed by a signed or unsigned integer
indicating the power of ten. Some examples of this notation are shown below:
· 656,000 = 6.56E5
· -0.0000135 = -1.35E-5
· 8,460,000 = 8.46E6
SPICE is a powerful general purpose analog and mixed-mode circuit simulator that is used to verify
circuit designs and to predict the circuit behavior. This is of particular importance for integrated circuits.
It was for this reason that SPICE was originally developed at the Electronics Research Laboratory of the
University of California, Berkeley (1975), as its name implies: Simulation Program for Integrated Circuits
Emphasis
PSpice is a PC version of SPICE (which is currently available from OrCAD Corp. of Cadence Design
Systems, Inc.).
SPICE can do several types of circuit analyses. Here are the most important ones:
• Non-linear DC analysis: calculates the DC transfer curve.
• Non-linear transient and Fourier analysis: calculates the voltage and current as a function of time
when a large signal is applied; Fourier analysis gives the frequency spectrum.
• Linear AC Analysis: calculates the output as a function of frequency. A bode plot is generated.
• Noise analysis
• Parametric analysis
• Monte Carlo Analysis
In addition, PSpice has analog and digital libraries of standard components (such as NAND, NOR, flipflops,
MUXes, FPGA, PLDs and many more digital components, ). This makes it a useful tool for a wide
range of analog and digital applications. All analyses can be done at different temperatures. The default
temperature is 300K.
The circuit can contain the following components:
• Independent and dependent voltage and current sources
• Resistors
• Capacitors
• Inductors
• Mutual inductors
• Transmission lines
Operational amplifiers
• Switches
• Diodes
• Bipolar transistors
• MOS transistors
• JFET
• MOSFET
• Digital gates
For further details refer user manual of PSPICE
All analysis can be done in different temperatures but the default is 300K.
Some Facts and Rules about PSpice
· PSpice is not case sensitive. This means that names such as Vbus, VBUS, vbus and even vBuS are
equivalent in the program.
· All element names must be unique. Therefore, you can't have two resistors that are both
named "R1," for example.
· There must be a node designated "0." (Zero) This is the reference node against which all
voltages are calculated.
· Each node must have at least two elements attached to it.
PSpice is a computer program used mostly by engineers and scientists. Accordingly, it was created with
the ability to recognize the typical metric units for numbers. Unfortunately, PSpice cannot recognize
Greek fonts or even upper vs. lower case. Thus our usual understanding and use of the standard metric
prefixes has to be modified. For example, in everyday usage, "M" indicates "mega" (106) and "m" stands
for milli (10-3). Clearly, this would be ambiguous in PSpice, since it is not case sensitive. Thus, in PSpice,
a factor of 106 is indicated by "MEG" or "meg." "M" or "m" is reserved for 10-3. Another quirk of PSpice
is the designation for 10-6. In most publications, the Greek letter, μ, is used for this multiple. Since
there can be no Greek fonts (or any other special font designations) in PSpice, the early developers of
PSpice borrowed a trick from those who used typewriters. Before the IBM Selectric typewriter was
introduced, most writers of technical papers had to improvise for Greek letters. Since the Latin letter
"u" (at least in lower case) sort of resembled the lower case Greek μ, it was widely used as a substitute
for μ. Hence, either "U" or "u" stands for 10-6 in PSpice. Without further background explanations,
these are the metric prefix designations used in PSpice:
Number Prefix Common Name
· 1012 - "T" or "t" tera
· 109 - "G" or "g" giga
· 106 - "MEG" or "meg" mega
· 103 - "K" or "k" kilo
· 10-3 - "M" or "m" milli
· 10-6 - "U" or "u" micro
· 10-9 - "N" or "n" nano
· 10-12 - "P" or "p" pico
· 10-15 - "F" or "f" femto
An alternative to this type of notation, which is in fact, the default for PSpice output data, is "textual
scientific notation." This notation is written by typing an "E" followed by a signed or unsigned integer
indicating the power of ten. Some examples of this notation are shown below:
· 656,000 = 6.56E5
· -0.0000135 = -1.35E-5
· 8,460,000 = 8.46E6
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