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SPICE USING LTSPICE DR. ASLAN TEXAS STATE UNIVERSITY OUTLINE • Introduction to SPICE • DC Analysis • Transient Analysis • AC Analysis • Subcircuits • Optimization • Power Measurement INTRODUCTION TO SPICE • Simulation Program with Integrated Circuit Emphasis • Developed in 1970’s at Berkeley • Many commercial versions are available • HSPICE is a robust industry standard • Has many enhancements that we will use • Written in FORTRAN for punch-card machines • Circuits elements are called cards • Complete description is called a SPICE deck WRITING SPICE DECKS • Writing a SPICE deck is like writing a good program • Plan: sketch schematic on paper or in editor • Modify existing decks whenever possible • Code: strive for clarity • Start with name, email, date, purpose • Generously comment • Test: • Predict what results should be • Compare with actual • Garbage In, Garbage Out! SOME FACTS AND RULES ABOUT SPICE • • • • • • • Spice is not case sensitive. Rsource and RsOuRcE and RSOURCE are equivelent. All element names must be unique. You can't have two capacitors that both are named “C1”. The first line in the data file is used as a title. Spice will ignore this line as circuit data. Put your name and title. 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. The last line in any data file must be ".END" (a period followed by the word "end.") All lines that are not blank (except for the title line) must have a character in column 1, the leftmost position on the line. • Use "*" (an asterisk) in column 1 in order to create a comment line. • Use "+" (plus sign) in column 1 in order to continue the previous line (for better readability of very long lines). • Use "." (period) in column 1 followed by the rest of the "dot command" to pass special instructions to the program. • Use the designated letter for a part in column 1 followed by the rest of the name for that part (no spaces in the part name). • Use "whitespace" (spaces or tabs) to separate data fields on a line. • Use ";" (semicolon) to terminate data on a line if you wish to add commentary information on that same line. SPICE ELEMENTS UNITS Letter Unit Magnitude a atto 10-18 f fempto 10-15 p pico 10-12 n nano 10-9 u micro 10-6 m mili 10-3 k kilo 103 x mega 106 g giga 109 Ex: 100 femptofarad capacitor = 100fF, 100f, 100e-15 SOURCES - DC <source name> <positive node> <negative node> <source model> • DC Source Vname N1 N2 Type Value Iname N1 N2 Type Value Vs 1 0 DC 20V Is 0 4 DC 50MA Va vs VWX vwx Vdep 4 qe 23 14 15 2 qc 14 23 27 DC dc 18k DC DC 16.0V 24m ; "V" after "16.0" is optional ; "QE" is +node & "qc" is -node ; "dc" not really needed -1.8E4 ; same as above 0V ; V-source used as ammeter SOURCES - AC • DC Source Vname n+ n- Type Value Phase (Deg) Iname n+ n- Type Value Phase (Deg) Vac 4 1 AC 120V 30 Vba 2 5 AC 240 Ix 3 6 AC 10.0A -45 Isv 12 9 AC 25mA ; phase angle 0 degrees ; phase angle -45 degrees ; 25 milliamps @ 0 degrees SOURCES – DEPENDENT • Voltage controlled voltage source: Ename n+ n- nc+ Ebar 17 8 42 18 efix 3 1 nc- Voltage Gain Value 24.0; gain is 24 0 11 -20.0; same as above Ellen 12 0 20 41 16.0 • Voltage controlled current source: Gname Glab 23 G1 12 Grad 19 Grad 19 Grad 40 n+ n- nc+ nc- 17 8 3 2.5 9 1 0 4E-2 40 6 99 0.65 40 99 6 -0.65 ; same as above 19 99 6 0.65 ; etc. Value SOURCES – DEPENDENT (CONT.) • Current controlled voltage source: Hname N1 N2 Vcontrol Value Hvx 20 12 Vhx Vhx 80 76 DC 50.0 0V ; controls Hvx Hab 10 0 V20 V20 15 5 DC 75.0 0V ; controls Hab HAL 20 99 Vuse 10.0 Vuse 3 5 DC 20V ; actual voltage source • Current controlled current source: Fname N1 Ftrn Vclt Fcur Vx F3 V1 81 23 63 33 2 3 N2 Vcontrol Value 19 Vctl 12 DC 48 Vx 71 DC 0 V1 1 DC 50.0 0V ; controls Ftrn 20.0 0V ; controls Fcur 15.0 0V ; controls F3 SOURCES – PULSE Vname n+ n- Pulse(V1 V2 Td Tr Tf Tw Period) V1 : Initial voltage V2 : Peak voltage Td : Initial delay time Tr : Rise time; Tf : Fall time; Tw : Pulse width Period : Period. Vs 1 0 Pulse(0V 10V 0 0.1 0.1 0.9 2) Vs 1 0 Pulse(0V 10V 0s 100ms 100ms 900ms 2s) Vs 1 0 Pulse(0 10 0 100m 100m 900m 2) SOURCES – SINUSOIDAL Vname n+ n- Sin(Vo Va fr Td Theta phase) Vname = Vo + Va e[-Theta.(t - Td)] sin[2pi.fr (t - Td) + (Phase/360)] Vo : Offset voltage in volt. Va : Amplitude in volt. fr : The frequency in Hz. Td : Delay in seconds Theta : Damping factor per second Phase : Phase in degrees Vs 1 0 SIN(2V 5V 2Hz 200ms 2Hz 30d) VG 1 2 SIN(5 10 50 0.2 0.1) VG2 3 4 SIN(0 10 50) SOURCES – PIECEWISE LINEAR SOURCE Vname n+ n- PWL(T1 V1 T2 V2 T3 V3 ...) T1 : Time for the first point V1 : Voltage for the first point T2 : Time for the second point V2 : Voltage for the second point Vgpwl 1 2 PWL(0 0 10U 5 100U 5 110U 0) CIRCUIT ANALYSIS - .OP • .OP (Operating Point Analysis) Example_OP.CIR Vs 1 0 DC 20.0V ; note the node placements Ra 1 2 5.0k Rb 2 0 4.0k Rc 3 0 1.0k Is 3 2 DC 2.0mA ; note the node placements .OP .END If you need some values use .PRINT DC V(3,2) I(Ra) CIRCUIT ANALYSIS - .TRAN • .TRANTransient Analysis * prt_stp t_max prt_dly max_stp .TRAN 20us 20ms 8ms 10us UIC 1. The following example performs and prints the transient analysis every 1 ns for 100 ns. .TRAN 1NS 100NS 2. The following example performs the calculation every 10 ns for 1 µs; the initial DC operating point calculation is bypassed, and the nodal voltages specified in the .IC statement (or by IC parameters in element statements) are used to calculate initial conditions. .TRAN 10NS 1US UIC CIRCUIT ANALYSIS - .TRAN Example_TRAN.cir Rp 0 1 1.0 Lp 1 0 8mH IC=20A Cp 1 0 10mF IC=0V .TRAN 500us 100ms 0s 500us UIC .PROBE .END DATA TRANSFER TO MATLAB Assume I have the previous circuit Example_TRAN.cir. After you run Simulate import your data to MATLAB for further analysis. In LTSpice go to now you can Change the file name. Keep the extension (mace it .xls if you want to open in excel) File → Export Highlight the data values (Transient analysis time will be added) Now you can open your MATLAB and relocate MATLAB directory where you saved “Example_ TRAN.txt” file. DATA TRANSFER TO MATLAB (CONT.) Now you can open your MATLAB and relocate MATLAB directory where you saved “Example_ TRAN.txt” file. In MATLAB command window type >> load Example_TRAN.txt will create and error. This is due to forst line of the txt file. Txt file xls file MATLAB cannot read that first line as data. Delete that line and save your file. Do not forget the order of the columns. (1st Column is time, 2nd I(Cp) and 3rd one is I(Lp)) >> load Example_TRAN.txt In workspace of MATLAB you will see the loaded data. It hae 202 rows and 3 columns. Next step we will save the data as time, I(Cp) and I(Lp). DATA TRANSFER TO MATLAB (CONT.) In workspace of MATLAB you will see the loaded data. It hae 202 rows and 3 columns. Next step we will save the data as time, I(Cp) and I(Lp). >> t=Example_TRAN(:,1); %This will save t as time variable >> I_Cp=Example_TRAN(:,2); %This will save I_Cp as time I(Cp) >> I_Lp=Example_TRAN(:,3); %This will save I_Lp as time I(Lp) Your work place shoul look like this Now we can plot these >> >> plot (t, I_Cp, t,I_Lp) CIRCUIT ANALYSIS - .AC * .AC .AC .AC type LIN LIN DEC #points 1 11 20 start 60Hz 100 1Hz stop 60Hz; <== what we want now. 200; <== a linear range sweep 10kHz; <== a logarithmic range sweep .PRINT AC VM(30,9) VP(30,9); magnitude & angle of voltage .PRINT AC IR(Rx) II(Rx); real & imag. parts Rx current .PRINT AC VM(17) VP(17) VR(17) VI(17); the whole works on node 17 CIRCUIT ANALYSIS - .AC Example_AC.cir Vs 1 0 AC 120V 0 Rg 1 2 0.5 Lg 2 3 3.183mH Rm 3 4 16.0 Lm 4 0 31.83mH Cx 3 0 132.8uF .AC LIN 1 60 60 .PRINT AC VM(3) VP(3) IM(Rm) IP(Rm) IM(Cx) IP(Cx) .END CIRCUIT ANALYSIS - .AC First-order low-pass RC filter Vin 1 0 AC 1.0V Rf 1 2 1.59 Cf 2 0 100uF .AC DEC 20 100Hz 100kHz .PROBE .END Second-Order High-Pass Filter Vin 1 0 AC 10V Rf 1 2 4.0 CF 2 3 2.0uF Lf 3 0 127uH .AC DEC 20 100Hz 1MEG .PROBE .END SUBCIRCUITS * name nodelist .SUBCKT Example_1 5 12 18 Iw 10 12 DC 10A Ra 5 12 5.0 Rb 5 13 4.0 Rc 12 13 2.0 Rd 5 18 8.0 Re 13 18 3.0 Rf 10 13 1.0 Rg 10 18 6.0 .ENDS Subcircuit Example No. 1 * name nodelist .SUBCKT Example_1 5 12 18 Iw 10 12 DC 10A Ra 5 12 2.0 Rb 5 13 5.0 Rc 12 13 2.0 Rd 5 18 8.0 Re 13 18 3.0 Rf 10 13 1.0 Rg 10 18 6.0 .ENDS Vs 1 0 DC 50V Ra 1 2 1.0 ; different from Ra above Rb 3 4 3.0 ; different from Rb above Rc 7 0 25.0 ; different from Rc above Rd 6 0 45.0 ; different from Rd above * nodelist name X1 2 7 3 Example_1 X2 4 6 5 Example_1 .END SUBCIRCUITS .SUBCKT OpAmp p_in n_in com out Ex int com p_in n_in 1e5 Ri p_in n_in 500k Ro int out 50.0 .ENDS Subcircuit Example No. 2 - Inverting OpAmp .SUBCKT OpAmp p_in n_in com out Ex int com p_in n_in 1e5 Ri p_in n_in 500k Ro int out 50.0 .ENDS Vg 1 0 DC 50mV Rg 1 2 5k Rf 2 3 50k RL 3 0 20k X1 0 2 0 3 OpAmp .END CIRCUIT ANALYSIS Voltage Divider Circuit VCC 4 0 DC 12V R1 4 1 10K R2 1 0 RMOD 1 .MODEL RMOD RES(R=1) .STEP RES RMOD(R) .1k, 15k, 1k RC 4 3 2.7K RE 2 0 1K Q1 3 1 2 Q2N3904 Model for 2N3904 NPN BJT (from Eval library in Pspice) .model Q2N3904 NPN(Is=6.734f Xti=3 Eg=1.11 Vaf=74.03 Bf=416.4 Ne=1.259 + Ise=6.734f Ikf=66.78m Xtb=1.5 Br=.7371 Nc=2 Isc=0 Ikr=0 Rc=1 + Cjc=3.638p Mjc=.3085 Vjc=.75 Fc=.5 Cje=4.493p Mje=.2593 Vje=.75 + Tr=239.5n Tf=301.2p Itf=.4 Vtf=4 Xtf=2 Rb=10) .OP .PRINT DC I(VCC) I(RC) .END CIRCUIT ANALYSIS Voltage Divider Circuit VCC 4 0 DC 12V R1 4 1 10K R2 1 0 RMOD 1 .MODEL RMOD RES(R=1) .STEP RES RMOD(R) .1k, 15k, 1k RC 4 3 2.7K RE 2 0 1K Q1 3 1 2 Q2N3904 .include bjt.lib .OP .PRINT DC I(VCC) I(RC) .END THEVENIN’S THEOREM Thevenin Example No. 1 Vs 2 5 DC 100V Vc 2 3 DC 0V; controls Fx Fx 6 7 Vc 4.0; gain = 4 * n+ n- NC+ NC gain Ex 2 1 5 4 3.0; gain = 3 R1 3 4 5.0 R2 4 7 5.0 R3 5 4 4.0 R4 7 0 4.8 R5 5 6 1.0 R10 1 0 1MEG; satisfies PSpice * out_var input_source .TF V(1,0) Vs .END REFERENCES • http://www.uta.edu/ee/hw/pspice/ • http://cmosedu.com/ • http://www.seas.upenn.edu/~jan/spice/spice.overview.html#Output