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EENG 2920: Circuit Design and Analysis Using PSpice Class 3: DC and Transient Analysis Oluwayomi Adamo Department of Electrical Engineering College of Engineering, University of North Texas 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. EENG 2920, Class 3 2 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: RES RVALUE R [1 TC1 (T-T 0) TC 2 (T T 0) 2 ] 1.01TCE (T-T 0) T and T0 are the operating temperature and the room temperature, respectively, in degree Centigrade EENG 2920, Class 3 3 EENG 2920, Class 3 4 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 6Vdc Label breakout resistor models Run simulations Show voltages and currents Edit model parameters Also demonstrate how to edit property R1 6.00 0V 3.00 0mA V1 R1 6.00 0V 3.00 0mA V1 R2 3.00 0V 3.00 0mA Rbre ak 1k Rbre ak 1k 3.00 0mA 0V 0 R2 3.30 0V 3.00 0mA Rmo d1 1k Rmo d2 1k 6Vdc 3.00 0mA 0V 0 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. EENG 2920, Class 3 5 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: 20Vd c R1 R2 1 2 3 500 Rmo d1 Vs 1k 800 Rmo d1 R3 Rmo d2 200 R4 Rmo d2 IDC 50m Adc 0 EENG 2920, Class 3 6 Create simulation profile “sim1” Analysis type is “Bias Point” Run simulation, show the following simulation results Figure 3.2.1: R1 1 20.0 0V 15.7 3mA R2 2 11.7 4V 500 Rmo d1 15.7 3mA 20V dc 3 13.0 5mA Vs 1k 9.48 4V 800 2.68 7mA Rmo d1 52.6 9mA R3 Rmo d2 200 R4 Rmo d2 50.0 0mA IDC 50m Adc 0V 0 Try the following menu commands PSpice – Bias Points PSpice – Create Netlist, and PSpice – View Netlist EENG 2920, Class 3 7 Example 3.3 Create a new blank Analog or Mixed A/D project E3_2 R1 R2 Draw the following circuit: 1 2 Define node numbers: 1, 2, 3, 4. 5 Vin 10V dc 3 10 R3 20 R4 40 Is 2Ad c R5 4 Create a new simulation profile sim1 10 0 Analysis type is Bias Point Define parameters to Calculate Small Signal DC Gain (.TF) as shown in the figure: Vin V(2,4) EENG 2920, Class 3 8 Run simulation and obtain the following simulation results: R1 R2 1 10.0 0V 2 5 3 500. 0mA 10 23.7 5V 1.12 5A 12.5 0V 500. 0mA Figure 3.3.1: 625. 0mA Vin 10Vd c 875. 0mA R3 20 R4 40 Is 2Adc 2.00 0A R5 0V 1.12 5A 4 -11.2 5V 10 0 Check Output File for the Small Signal Characteristics Go to menu PSpice – View Output File: Figure 3.3.2: EENG 2920, Class 3 9 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. EENG 2920, Class 3 10 Capacitor i (t ) i v R v (t ) C v iR 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) dv(t ) dt The symbol for a capacitor is C. The name of a capacitor must start with C, and the general form is: i (t ) C 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: CAP CVALUE C (1 VC1V VC 2 V 2 ) [1 TC1 (T-T 0) TC 2 (T T 0) 2 ] T and T0 are the operating temperature and the room temperature, respectively, in degree Centigrade 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) EENG 2920, Class 3 11 i (t ) Inductor v (t ) L v(t ) L 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) di (t ) dt 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: IND LVALUE L (1 IL1 I IL 2 I 2 ) [1 TC1 (T-T 0) TC 2 (T T 0) 2 ] T and T0 are the operating temperature and the room temperature, respectively, in degree Centigrade 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) EENG 2920, Class 3 12 Exponential Source The symbol of exponential sources is EXP, and the general form is Model parameters (Table 4.3, page 91) EXP (V1 V2 TRD TRC TFD TFC) 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. EENG 2920, Class 3 13 Pulse Source The symbol of pulse sources is PULSE, and the general form is Model parameters (Table 4.4, page 92) PULSE (V1 V2 TD TR TF PW PER) 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. EENG 2920, Class 3 14 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 EENG 2920, Class 3 15 Single-Frequency Frequency Modulation The symbol for a source with single frequency modulation is SFFM, and the general form is Model parameters (Table 4.6, page 95) SFFM (VO VA FC MOD FS) 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. EENG 2920, Class 3 16 Sinusoidal Source The symbol for sinusoidal source is SIN, and the general form is Model parameters (Table 4.7, page 96) SIN (VO VA FREQ TD ALP THETA) 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: V VO VAe (t td ) sin[ 2f (t t d ) ] EENG 2920, Class 3 17 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 2.0V To show how to copy clearly visible plots to Word. R1 1 L1 2 1 2 3 2 50uH V 0V V 2 V1 C1 IC = 2V 10uF 1 Figure 4.1.2 -2.0V 0s Figure 4.1.1 0 EENG 2920, Class 3 250us V(3) V(1) Time 500us 18 Example 4.2 L1 2 1 50uH V1 V1 = -220 V2 = 220 TD = 0 TR = 1ns TF = 1ns PW = 100us PER = 200u s The voltage source is VPULSE from “source.olb” Add a voltage marker and a current marker 2 3 V C1 10uF 0 Create a new simulation profile R1 2 1 I Draw a circuit as shown in the figure: Figure 4.2.1: Analysis type is “Time Domain (Transient)” Run to time: 400us Maximum step size: 1us Run simulation to obtain the results: 200A 0A SEL>> -200A I(R1) 400V In PSpice AD, use menu command “Plot – Add Plot to Window ” to add a new plot in the same window. 0V -400V 0s Figure 4.2.2: 100us 200us V(3) Time 300us 400us EENG 2920, Class 3 19 Example 4.3 2 Vin1 L2 1 1 50uH V V R3 2 L3 1 8 50uH V Vin2 C1 10uF 2 50uH V Vin3 C2 10uF C3 10uF Select VPWL device, right-click mouse, select “Edit Properties …” Create a new simulation R2 2 The source is Figure 4.3.1 VPWL from “source.olb” 0 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: L1 1 Draw circuit: R1 Analysis type is Time Domain (Transient) Run to time: 400us Maximum step size: 1us 1.5V 1.0V Run simulation to obtain the result: Please observe how the circuits respond to the same step input voltage signal. 0 . 5 V 0V 0s Figure 4.3.2: EENG 2920, Class 3 V(L1:2) 100us V(L2:2) 200us V(R1:1) Time 300us V(L3:2) 400us 20 Example 4.4 Figure 4.4.1: R1 L1 1 2 1 2 2 3 50uH V I Vin Draw circuit: C1 The source is VSIN from “source.olb” The parameters of VSIN is shown in the circuit. 10uF 0 Create a new simulation VOF F = 0 VAMPL = 1 0 FRE Q = 5k Hz Analysis type is Time Domain (Transient) Run to time: 500us Maximum step size: 1us Run simulation to obtain the result: 4.0A 0A SEL>> -4.0A I(R1) 20V 0V -20V Figure 4.4.2: 0s 250us 500us V(3) Time EENG 2920, Class 3 21 Example 4.5 R1 1 L1 2 V 6 IC = 3A 3 1 RMO D 1.5m H 2 LMO D V 2 Vin Draw circuit as shown in figure: 2.5u F CMO D R2 2 RMO D 1 R, L, C are all from “breakout.olb” Define models RMOD, LMOD, and CMOD as shown in the figure on the Figure 4.5.1 bottom. Use the new models in the circuit. 0 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 C1 IC = 4V Analysis type is: Time Domain (Transient). Run to time: 1ms, Max step size: 5us. 20V Temperature (sweep): Run at 50°C. Obtain the simulation result in the figure: 10V 0V -10V 0s EENG 2920, Class 3 0.5ms V(1) V(3) Time 1.0ms 22 Figure 4.5.2 Example 4.6 R1 L1 1 2 6 3 RMO D 1.5m H LMO D V 2 Vin C1 IC = -4V Repeat Example 4.5 with the following difference: 2.5u F CMO D R2 2 RMO D 1 L1 has no initial condition The initial condition for C1 has been changed to -4V. Figure 4.6.1 0 Notice that the response is completely different from Example 4.5, because the initial conditions of L and C are different. 4.0V 2.0V Figure 4.6.2 0V 0s 0.5ms 1.0ms V(3) Time EENG 2920, Class 3 23