Dependent Sources
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Transcript of Dependent Sources
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in Cadence/OrCAD PSpice
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Objective of LectureIntroduce the parts in PSpice for dependent
voltage and current sources.Describe how to set the part properties to set
the coefficient a for the dependent source.Explain some issues that arise when
connecting these parts in the schematics layout tool in PSpice.
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Dependent SourcesType of Source Acrony
mSymbol in Text
Part Name in PSpice
Symbol in PSpice
Voltage Controlled
Voltage Source VCVS E
Current Controlled
Current Source CCCS F
Voltage Controlled
Current SourceVCCS G
Current Controlled
Voltage SourceCCVS H
where a is a cofficient and I and V are the current and voltage at some other point in the circuit.
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CCCSImplementation in PSpice
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Part FDouble click on F to set the value of the
coefficient (a = 3 in this example) that is multiplied by the current through R1 to set the current through the dependent current source.
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Layout IssuesWrong: The dependent current source will act as a short across R1
Correct: The current that flows through R1 enters the dependent current source.
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Layout IssuesTo implement the circuit exactly in PSpice,
the wires to Part F had to criss-cross each other on the input and output terminals in order to get the direction of the arrows to follow the direction of the currents in the original circuit.
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Layout IssuesBoth of the wires were extended out laterally from Part F before running one across the other wire.
If this was not done, a connection between the terminal on Part F would have been automatically made. A node – dot – would show up on the circuit schematic), creating a short between the two wires.
Node created by criss-
crossing wires
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Layout IssuesTo minimize running wires like this, you can
change the orientation of the part in the circuit.
Keystroke shortcuts in OrCAD PSpice Cnt-R is Rotate Cnt-F is Flip Cnt-M is Mirror
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Layout IssuesOriginal layout
After rotating and flipping Part F.
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Layout IssuesAlternatively, you can changed the sign on
the coefficient, F, on Part F to eliminate one of the criss-crossing connections.
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VCVS
The connections for the reference voltage used to set the voltage controlled voltage source are made across the component with the sides on the part matching the signs for VR on the circuit.
Implementation in PSpice
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CCVSImplementation in
PSpice
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VCCSImplementation in
PSpice
Changing the sign on the coefficient of the reference voltage in Part G eliminated the need to criss-cross wires on the current
source side of the VCCS.
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SummaryThe names of the parts in PSpice that are
dependent sources have been identified and the way to modify the coefficient a was demonstrated.VCVS: Part ECCCS: Part FVCCS: Part GCCVS: Part H
The control portion of the part is incorporated into the circuit in the same manner that a voltage or current measurement is made using a digital multimeter.