MultiSIM BLUE SPICE Simulation Introduction The MultiSIM BLUE circuit design platform enables functional simulation using the latest Berkeley SPICEengine . A key attribute in MultiSIM BLUE is the ability to visualize the simulation using virtual instruments such as function generators, digital multimeters and oscilloscopes. In addition the MultiSIM BLUE platform enables you to use pre-created LabVIEW instruments that allow you to enable more measurement capability and to interact with your design in unique ways. What is SPICE? SPICE is a high level, text based circuit description syntax allowing circuit designers to mathematical describe the components and connections that make up their circuit. MultiSIM BLUE automatically generates a SPICE netlist in the background (for those parts containing a SPICE model) and then has a built-in SPICE engine solver to predict the overall circuit behavior in various modes. SPICE requires individual components to have a simulation model allowing behavior of the individual components. The level of detail in the model allows the user to perform f circuit simulation with different tiers of accuracy. The most complex SPICE models can model noise, AC, low level DC and transient effects within a circuit whereas ideal models can predict pure mathematical behavior of a device. Ideal models allow the user to simplify the circuit components into the most basic or intrinsic behavior (such as a diode exhibiting current flow in only a single direction). Basic or virtual models are simplified models that exhibit basic DC, transient and in some cases basic first order AC response. Basic simulation models are generally useful in standard circuit configurations, The highest quality simulation models are created by the component manufacturers. These will allow the most accurate simulations including low level or detailed frequency domain analyses. The MultiSIM BLUE platform use a combination of all three of these model types, and does allow for some level of tuning by the user, though not recommended on the manufacturer created models. Shown below is a schematic of a simple amplifier circuit using a general time domain (transient) simulation using components in the MultiSIM BLUE NI Component Evaluator Mouser Edition software. Note that there are various types of components and symbols used in this schematic. The blue components are the ones that simulate (SPICE model) and have a footprint for PCB layout. The black colored components are for use in simulation (such as the AC voltage generator). The green components (connectors in this example) are connected in this circuit and are used for PCB layout (they have a mapped footprint), however they are not used in the simulation.

To begin the simulation in interactive mode, press the green run arrow ( ). In the example a virtual oscilloscope is connected into the circuit to visualize the behavior of the circuit in the time domain. Open the front panel of the oscilloscope by double-clicking on the oscilloscope icon and its window will open. Many components in MultiSIM BLUE are interactive (such as potentiometers and switches) and others (such as LEDs and fuses) will animate during the simulation, allowing you to visualize the basic functionality of your schematic. To perform other measurements will the simulation is running in interactive mode, other instrument devices in MultiSIM BLUE work in a similar interactive fashion, although they can invoke different analyses or simulation capabilities. On the the instruments, it is worth noting that the terminal connectors are important on the virtual instruments as some of these can be assumed to be at ground (such as the negative terminal on the oscilloscope), unless its connected to a net as a reference. Shown below is a single ended (ground referenced measurement) and a differential measurment (voltage across the resistor).

(ground referenced) (differential)

While the simulation is running you can interact with some of the virtual instrument types such as the oscilloscope, function generator and DMM. Some others require you to restart the simulation such as the bode plotter (which runs a frequency sweep or AC analysis on the circuit). Virtual Instruments Built In Virtual Instruments in MultiSIM BLUE (Mouser Edition) are described below in the order shown in the instrument shortcut menu.

Instrument (Icon)

Symbol Front Panel Purpose (Pins)

Multimeter

( )

Measures Voltage, Current, Resitance and dB (ref)

Pins: (+) = Positive (-) = Negative

Function Generator

( )

Generates waveforms with adjustable settings. Allows

custom waveforms in interactive mode

Pins: (+) = Non-Inverting Output (Common) = Ground (-) = Inverting Output

Wattmeter

( )

Measures power in Watts using Voltage and Current

signals

Pins: Voltage (+) (-) = Differential Voltage Current (+) (-) = Series Current

Oscilloscope

( )

2 channel waveform measurements with trigger

Pins: A (+) (-) = Voltage CH A B (+) (-) = Voltage CH B Ext Trig (+) (-) = External Trigger Signal Note: If connected (-) will yield a differential measurement, otherwise (+) will reference to ground

Four channel

Oscilloscope

( )

4 channel waveform with trigger

Pins: A = Voltage CH A B = Voltage CH B C = Voltage CH C D = Voltage CH D G = Gate T = Trigger

Note: Signals are referenced to ground

Bode Plotter

( )

Bode plotter allowing a frequency sweep analysis to be performed (such as for a

filter)

Pins: IN (+) (-) = Input signal OUT (+) (-) = Output signal

Note: Signal is referenced to ground if (-) is not connected. Default analysis is showing Mag(f) = Vout / Vin and the result is shown in dB

Word Generator

( )

Word generator is used for testing digital or mixed

simulation

Pins: 0-31 = Digital Output R = Ready T = Trigger

Logic Analyzer

( )

Logic Analyzer is a digital measurement devices that captures digital patterns

from a simulation

Pins: 1-F = 16 Digital Inputs C = External Clock Q = Qualifier T = Trigger

IV Analyzer

( )

IV instrument performs a DC sweep and anlyzers the

current and voltage behavior of 2 and 3 pin discrete semiconductor

devices

Pins: (dynamic) P, N (diode) B, E, C (transistor) G, S, D (mosfet)

Interactive Probe

( )

None (embedded with circuit)

Inline probe. Can also be used while

simulation is running as a meter for simulation

LabVIEW VI

( )

Various (each VI as a unique user interface)

The GUI is unique to each

instrument. Custom LabVIEW instruments can

be downloaded from the NI website to add more

measurements to Multisim

Current Probe

( )

None (terminal with current reading scaled as a voltage)

This probe is useful for

making time domain current measurements

using the oscilloscope. The reading can be scaled (caution as the default

scaling factor is set as 1 V per mA)

Interactive Components There are many interactive and animated components in Multisim. Shown below are a few samples.

Component Type (Database Location)

Symbol Interactive Behavior

Interactive DC Source (Sources ->

SIGNAL_VOLTAGE_SOURCES)

By clicking near the Voltage level you can adjust the DC

level during simulation

LED (Diodes -> LED)

After configuring the device, the device will illuminate when

the simulation is running if there is sufficient on current

Switch (Basic -> SWITCH)

OR

(Electro_Mechanical ->

SUPPLEMENTARY_SWITCHES)

OR

While simulating you can adjust the switch (open or

closed). Other switch types are available

Potentiometer (Basic -> POTENTIOMETER)

You can adjust the wiper position (shown as a % value)

during simulation

Virtual Lamp (Indicators -> VIRTUAL_LAMP)

The device will emulate a lamp that will turn on/off based on

applied power