EENG 2920: Circuit Design and Analysis Using PSpice Class 3: DC and Transient Analysis Oluwayomi Adamo Department of Electrical Engineering College of

EENG 2920: Circuit Design and Analysis Using PSpiceClass 3: DC and Transient Analysis

Oluwayomi AdamoDepartment of Electrical EngineeringCollege of Engineering, University of North Texas

EENG 2920, Class 3 2

Modeling of Elements

PSpice simulation of circuits is based on the models of circuit elements.

A model that specifies a set of parameters for an element is specified in PSpice by the “.MODEL” command. The general form of the model statement is

.MODEL MNAME TYPE (P1=A1 P2=A2 …)TYPE is the type name of the elements and must have the correct model type name (shown in Table 3.2, page 43)

There can be more than one model of the same type in a circuit with different model names.


Resistor Models The name of a resistor must start with R. Models in PSpice Capture

The user can assign the model name of the breakout devices in the library “breakout.olb”

The user can edit the model parameters. Model Parameters for Resistors (Table 3.1, page 41)

R: Resistance, no unit, default: 1. TC1: linear temperature coefficient, unit: oC-1, default: 0. TC2: quadratic temperature coefficient, unit: oC-2, default: 0. TCE Exponential temperature coefficient, unit: oC-1, default: 0.

Resistance as a function of temperature:

T and T0 are the operating temperature and the room temperature, respectively, in degree Centigrade

)0(2 011])0(2)0(11[ T-TTCE.TTTCT-TTCRRVALUERES



A Simple Demo of PSpice Model Editor This step-by-step demo will show how to do the following:

Add library breakout.olb Place breakout elements, e.g., Rbreak Invoke PSpice Model Editor Create new resistor models Label breakout resistor models Run simulations Show voltages and currents Edit model parameters Also demonstrate how to edit property

3.000V

0V

0

R1

Rbreak1k

3.000mA

V16Vdc

3.000mA

R2

Rbreak1k

3.000mA6.000V

V16Vdc

3.000mA

0

6.000VR2

Rmod21k

3.000mA3.300V

0V

R1

Rmod11k

3.000mA

Note: In the Capture CIS that we are using in labs, we have to write “R=.9”, instead of “R=0.90”; that is, you have to remove 0 at both ends. The Lite version does not have such bugs.


Example 3.2 Create a new blank Analog or Mixed A/D project E3_2 Draw the following circuit:

Resistors are from the library “breakout.olb”, Rbreak Select one of the Rbreak resistor, right-click mouse, select “Edit PSpice Model” Create resistor models Rmod1 and Rmod2, save the models:

Correctly label the breakout resistor models:

3

R4Rmod2

200

R2

Rmod1800

0

21

IDC

50mAdc

Vs20Vdc R3Rmod21k

R1

Rmod1500


Create simulation profile “sim1” Analysis type is “Bias Point”

Run simulation, show the following simulation results

Try the following menu commands PSpice – Bias Points PSpice – Create Netlist, and PSpice – View Netlist

0V

3

Vs20Vdc

15.73mA

R4Rmod2

200

52.69mA

R2

Rmod1800 2.687mA

220.00V

IDC

50mAdc

50.00mA

R3Rmod21k

13.05mA

1

0

11.74V 9.484VR1

Rmod150015.73mA

Figure 3.2.1:


Example 3.3 Create a new blank Analog or Mixed A/D project E3_2 Draw the following circuit:

Define node numbers: 1, 2, 3, 4.

Create a new simulation profile sim1 Analysis type is Bias Point Define parameters to

Calculate Small Signal DC Gain (.TF) as shown in the figure:

R1

5

R5

10

Vin10Vdc

3

0

R320

R2

10

4

Is

2Adc

R440

21

VinV(2,4)


12.50V

2

Is

2Adc

2.000A

0

R320

625.0mA

R440

875.0mA

R5

10

1.125A0V

3

4

R2

101.125A

Vin10Vdc

500.0mA

R1

5500.0mA

-11.25V

10.00V 23.75V1

Run simulation and obtain the following simulation results:

Check Output File for the Small Signal Characteristics Go to menu PSpice – View Output File:

Figure 3.3.1:

Figure 3.3.2:


Transient Analysis

A transient analysis deals with the behavior of an electric circuit as a function of time.

If a circuit contains an energy storage elements, a transient can also occur in a DC circuit after a sudden change due to switches opening and closing.

PSpice allows simulating transient behaviors, by assigning initial conditions to circuit elements, generating sources, and the opening and closing of switches.

The simulation of transients in circuits with linear elements requires modeling of Resistors, capacitors, and inductors, Model parameters of elements, Operating temperature, Transient sources.


Capacitor

The symbol for a capacitor is C. The name of a capacitor must start with C, and the general form is: C<name> N+ N- CNAME CVALUE IC=V0

where IC is the initial condition, i.e., the initial voltage of the capacitor. Model parameters for capacitors (Table 4.1, page 86)

C: capacitance multiplier, no unit, default: 1. VC1: linear voltage coefficient, unit: V-1, default: 0. VC2: quadratic voltage coefficient, unit: V-2, default: 0. TC1: linear temperature coefficient, unit: oC-1, default: 0. TC2: quadratic temperature coefficient, unit: oC-2, default: 0.

Capacitance as a function of voltage and temperature:


The capacitor device from “breakout.olb” can be edited and new models can be defined in the same way as resistor. For example, .MODEL Cmod1 CAP (C=1 VC1=0.01 VC2=0.002 TC1=0.02 TC2=0.005)

iRv

Rv

i

C)(tv

)(ti

])0(2)0(11[)211( 22 TTTCT-TTCVVCVVCCCVALUECAP

dt

tdvCti

)()(


Inductor

The symbol for an inductor is L. The name of an inductor must start with L, and the general form is: L<name> N+ N- LNAME LVALUE IC=I0

where IC is the initial condition, i.e., the initial current of the inductor. Model parameters for inductors (Table 4.2, page 88)

L: inductance multiplier, no unit, default: 1. IL1: linear current coefficient, unit: A-1, default: 0. IL2: quadratic current coefficient, unit: A-2, default: 0. TC1: linear temperature coefficient, unit: oC-1, default: 0. TC2: quadratic temperature coefficient, unit: oC-2, default: 0.

Inductance as a function of voltage and temperature:


The inductor device from “breakout.olb” can be edited and new models can be defined in the same way as resistor and capacitor. For example, .MODEL Lmod1 IND (L=1 IL1=0.1 IL2=0.002 TC1=0.02 TC2=0.005)

L)(tv

)(ti

dt

tdiLtv

)()(

])0(2)0(11[)211( 22 TTTCT-TTCIILIILLLVALUEIND


Exponential Source The symbol of exponential sources is EXP, and the general form is

EXP (V1 V2 TRD TRC TFD TFC) Model parameters (Table 4.3, page 91)

V1: initial voltage, unit: V, default: none V2: pulsed voltage, unit: V, default: none TRD: rise delay time, unit: S, default: 0 TRC: rise-time constant, unit: S, default: TSTEP TFD: fall delay time, unit: S, default: TRD+TSTEP TFC: fall-time constant, unit: S, default: TSTEP

Among the parameters, V1 and V2 must be specified by the user.


Pulse Source The symbol of pulse sources is PULSE, and the general form is

PULSE (V1 V2 TD TR TF PW PER) Model parameters (Table 4.4, page 92)

V1: initial voltage, unit: V, default: none V2: pulsed voltage, unit: V, default: none TD: delay time, unit: S, default: 0 TR: rise time, unit: S, default: TSTEP TF: fall time, unit: S, default: TSTEP PW: pulse width, unit: S, default: TSTOP PER: period, second, default: TSTOP

Among the parameters, V1 and V2 must be specified by the user. TSTEP and TSTOP are the incrementing time and stop time, respectively, during the transient analysis.


Piecewise Linear Source

The symbol of piecewise linear sources is PWL, and the general form is PWL (T1 V2 T2 V2 … TN VN) A point in a waveform can be described by (Ti, Vi) or (Ti, Ii) and every

pair of values specifies the source value at time Ti. The voltage at time between the intermediate points is determined by PSpice using linear interpolation.

Model parameters (Table 4.5, page 94) Ti: time at a point, unit: second, default: none Vi: voltage at a point, unit: V, default: none


Single-Frequency Frequency Modulation The symbol for a source with single frequency modulation is SFFM,

and the general form is SFFM (VO VA FC MOD FS)

Model parameters (Table 4.6, page 95) VO: offset voltage, unit: V, default: none VA: amplitude of voltage, unit: V, default: none FC: carrier frequency, unit: Hz, default: 1/TSTOP MOD: modulation index, unit: none, default: 0 FS: signal frequency, unit: Hz, default: 1/TSTOP

Among the parameters, VO and VA must be specified by user and can be either voltages or currents.


Sinusoidal Source The symbol for sinusoidal source is SIN, and the general form is

SIN (VO VA FREQ TD ALP THETA) Model parameters (Table 4.7, page 96)

VO: offset voltage, unit: V, default: none VA: peak voltage, unit: V, default: none FREQ: frequency, unit: Hz, default: 1/TSTOP TD: delay time, unit: S, default: 0 ALPHA: damping factor, unit: 1/S, default: 0 THETA: phase delay, unit: degrees, default: 0

Among the parameters, VO and VA must be specified by user and can be either voltages and currents.

The waveform stays at 0 for a time of TD, and then the voltage becomes an exponentially damped sine wave. The exponentially damped sine wave is described by:

])(2sin[)( d

ttAO ttfeVVV d


PSpice Demo Draw circuit

To show how to set up PWL source parameters: T1=0, T2=1ns, T3=1ms, V1=0, V2=1, V3=1

To show how to display component pin ID. Simulation profile

Analysis type: Time Domain (Trasient) Run to time: 500us, Max step size: 1us

Menu command “Pivot” in property editor To show how to make the appearance of the Property Editor more user friendly.

“Copy to clipboard” in PSpice AD To show how to copy clearly visible plots to Word.

Time

0s 250us 500usV(3) V(1)

-2.0V

0V

2.0V

L1

50uH

1 2

V

V1

3

V

2R1

2

C1 10uFIC = 2V

1

2

0

1

Figure 4.1.2

Figure 4.1.1


Example 4.2 Draw a circuit as shown in the figure:

The voltage source is VPULSE from “source.olb” Add a voltage marker and a current marker

Create a new simulation profile Analysis type is “Time Domain (Transient)” Run to time: 400us Maximum step size: 1us

Run simulation to obtain the results:

Time

0s 100us 200us 300us 400usV(3)

-400V

0V

400VI(R1)

-200A

0A

200A

SEL>>

V1

TD = 0

TF = 1nsPW = 100usPER = 200us

V1 = -220

TR = 1ns

V2 = 220

I

R1 2

0

31

C1 10uF

V

2L1

50uH

1 2

In PSpice AD, use menu command “Plot – Add Plot to Window ” to add a new plot in the same window.

Figure 4.2.1:

Figure 4.2.2:


Example 4.3 Draw circuit:

The source is VPWL from “source.olb”

The parameters of VPWL is T1=0, T2=1ns, T3=1ms, V1=0, V2=1, V3=1. These parameters are set in the Property Editor: Select VPWL device, right-click mouse, select “Edit Properties …”

Create a new simulation Analysis type is Time Domain (Transient) Run to time: 400us Maximum step size: 1us

Run simulation to obtain the result: Please observe how the circuits respond

to the same step input voltage signal.

Time

0s 100us 200us 300us 400usV(L1:2) V(L2:2) V(R1:1) V(L3:2)

0V

0.5V

1.0V

1.5V

R3

8

C210uF

C110uF

L3

50uH

1 2L1

50uH

1 2R1

2

V

0

Vin3Vin1V V

Vin2

R2

1

C310uF

L2

50uH

1 2

V

Figure 4.3.1

Figure 4.3.2:


Example 4.4

Draw circuit: The source is VSIN from “source.olb” The parameters of VSIN is shown in the circuit.

Create a new simulation Analysis type is Time Domain (Transient) Run to time: 500us Maximum step size: 1us

Run simulation to obtain the result:

Time

0s 250us 500usV(3)

-20V

0V

20VI(R1)

-4.0A

0A

4.0A

SEL>>

0

C1 10uF

Vin

FREQ = 5kHzVAMPL = 10VOFF = 0

V

2L1

50uH

1 2

I

3R1

2

1Figure 4.4.1:

Figure 4.4.2:


3

LMOD

L1

1.5mH

IC = 3A1

2

R1

RMOD6

R2RMOD2

2

V V

CMODC1 2.5uF

IC = 4V1

2

1

Vin

0

Example 4.5 Draw circuit as shown in figure:

R, L, C are all from “breakout.olb” Define models RMOD, LMOD, and

CMOD as shown in the figure on thebottom. Use the new models in the circuit.

Define initial conditions (IC) of L and C in the property editor. The PWL voltage source is the VPWL from “source.olb”. The VPWL source

parameters are: (T1=0, T2=10ns, T3=2ms, V1=0, V2=10, V3=10) Create a new simulation profile

Analysis type is: Time Domain (Transient). Run to time: 1ms, Max step size: 5us. Temperature (sweep): Run at 50°C.

Obtain the simulation result in the figure:

Time

0s 0.5ms 1.0msV(1) V(3)

-10V

0V

10V

20V

Figure 4.5.1

Figure 4.5.2


Example 4.6 Repeat Example 4.5 with

the following difference: L1 has no initial condition The initial condition for C1

has been changed to -4V. Notice that the response is completely different from Example 4.5,

because the initial conditions of L and C are different.

Time

0s 0.5ms 1.0msV(3)

0V

2.0V

4.0V

2

R2RMOD2

V

1

0

LMOD

L1

1.5mH

3

CMODC1 2.5uF

IC = -4V1

2

R1

RMOD6

Vin

Figure 4.6.1

Figure 4.6.2

Documents

EENG 2920: Circuit Design and Analysis Using PSpice Class 3: DC and Transient Analysis Oluwayomi Adamo Department of Electrical Engineering College of