Multisim Tutorial

MULTISIM tutorial Introduction to MultiSim

Need For Simulation ❂

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For determination of parameters for complex circuits. To test validity of the circuit. Generate mathematical models of electronic components. Test performance without actually building the circuit . Calculating parameters of non-linear devices

Simulation Basics (Analog ckt)

G1 * e1 + (– k – G1)*e2 + k*e3 = I0 ……….(1) -G1*e1 + (G1 + G2 + G3)*e2 – G3*e3 = 0….(2) (-G3 + k)*e2 + (G4 + G3 – k)*e3 = 0………..(3)

Simulation Basics V1 1 0 10 SPICE input file: example R1 1 2 1.5k (Simulation Program with Integrated Circuit Emphasis) R2 2 0 1k  How many nodes?  Do we need extra variables (e.g., voltage sources)?  Assemble the system matrix.  Solve.

Simulation Basics (Digital ckt) Digital Circuits: event-driven simulation ❂ Instead of ckt description its behaviour is defined. ❂ Only discrete levels of voltage.

Components Available Basic : resistors , capacitor , inductor , potentiometer , transformer . ❂ Switches : SPST , SPDT , DPDT. ❂ Sources : DC power , AC power , Ground , Vcc , Vdd. ❂

….Components Diodes : Si / Ge diodes , Zener diodes , LED . ❂ Transistors : BJT ( npn and pnp) FET ( MOSFET & JFET ) ❂ Analog IC : operational amp (eg. IC 741) , Timer IC 555. And many more ❂

Digital Components Digital IC : available in TTL and CMOS families. ❂ Basic gates : 7408 (AND) , 7404 (NOT) , etc. ❂ MSI chips : 74151 (MUX) , 74138 (DEMUX) , 7483 (4 bit adder) , 7490 (dec counter) , etc. ❂ Indicators : HEX display , digital probe. ❂

Miscellaneous Components Crystals . ❂ Voltage regulators (eg. LM317 , 7805 , 7905). ❂ Fuse. ❂ RF Components. ❂ Transmission lines . ❂

Instruments ❂

Multimeter : for current , voltage and resistance measurements in ac and dc modes.

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Wattmeter : for power and power factor measurement.

…Instruments Function Generator : for generation of waveforms such as sinusoidal , square , triangular , with controls for frequency , duty cycle, amplitude ❂ Oscilloscope : to view output waveforms with controls for time base , Volt/div , trigger , X-Y mode and cursors 1 & 2 . ❂

Analysis of Circuits It is carried out to test the behaviour of the circuit for various inputs and/or varying conditions. ❂ Setting up of the output variables : Variables are nothing but nodes whose behavior is to be monitored . ❂ Setting of parameters to be varied. ❂

Types of Analysis DC Operat ing P oint A naly sis ❂ AC Ana lysis ❂ Transient Ana lysis ❂ Fou rier Ana lysis ❂ Noise Ana lysis ❂ Dis tor tion Ana lys is ❂ DC Swee p Ana lysis ❂

…Types of Analysis DC and AC Sensit ivit y A naly ses ❂ Paramet er Sweep Ana lysis ❂ Tem perat ure Sweep Ana lysis ❂ Transf er F unct io n A na lysis ❂ Pole Zer o A naly si s ❂ RF A na lyses ❂ (and more) ❂

DC operating point analysis In this analysis all the ac sources are zeroed out. ❂ Capacitors are assumed to be open, inductors short circuited. ❂ Used for Q point determination of amplifier stage. ❂

AC Analysis All input sources are automatically switched internally to a sinusoidal waveform for analysis. AC analysis then calculates the AC circuit response as a function of frequency. ❂ Used to calculate the Band width and/or Critical freq. ❂

Transient Analysis The circuit response is calculated as a function of time. ❂ Can be used to see the system response for a short duration of time [ eg. Time = 0 to 0.0001 seconds]. ❂ Used for observing step response of the system. ❂

Other Analyses... Parameter sweep : Specified parameter of the active device is varied. ❂ Temperature sweep : Operating temperature is varied. ❂ DC sweep analysis : The value from the source is incremented and another DC Operating Point is calculated. ❂

General steps for simulation Place components on the workspace . ❂ Connect components according to circuit diagram . ❂ Connect power supply and ground . ❂ Press the ‘ Simulation switch ’ ❂ Observe the results and carry out the required analyses. ❂

Some Special Features IC 555 Timer Wizard . ❂ Filter wizard. ❂ Dynamic measurement probe. ❂ Virtual Lab instruments and components . ❂ Dependant sources. ❂ Bill of materials. ❂

Precautions Each simulation must have a ground . ❂ Make sure all components are connected properly. ❂ Check all component values. ❂ Place HB/SB connector to labeling a node. ❂