Both methods of notation end up being translated in the same way, so it comes down to personal preference. For a stop time, you could use scientific notation and type in 5e-3s. This is explaining that you can use standard units in combination with scientific notification and multipliers to define specific frequency ranges or start values.įor example, if you were doing a transient analysis you could type in 1ms for the start time. Next, take a look at the bottom portion of the Simulation dialog, and you’ll see a text description about Multipliers. For example, if we were to enter a letter for the start value we’d get an error after selecting the Simulate button as shown below: This might seem obvious, but it’s good to point out that the simulation simply won’t run if you enter an invalid start or end value. EAGLE always checks for proper parameters in your selected simulation type before the simulation completes. sch file.īefore running our simulation, let’s talk about two quick points – range accuracy and multipliers. Every time you open the Configuration tab in a SPICE simulation and adjust settings, EAGLE saves a. One important thing to note is that all of these values come up as presets because there’s a SPICE simulation file saved in this project’s folder. Here we can see that DC sweep is the chosen simulation type with preconfigured Source, Start Value, and End Value parameters. We’ll begin by selecting the Simulation icon to open the Simulation dialog. With this circuit, we’ll be sweeping voltage from the FET gate to ground with a defined range of 0 to 10 volts. This schematic is a basic circuit that many beginner engineers use to learn what a FET is and what voltage curves look like in a SPICE simulation. Look for the Fet_Characterization project folder within the Projects » ngspice directory in your Autodesk EAGLE Control Panel. The example project we’ll be working with is a FET characterization schematic. By defining the start and stop voltage values we can get an accurate representation of how voltage fluctuates in specific scenarios. We’ll be using DC sweep to calculate our circuit’s bias point over a range of voltage values. Running these two simulations will also give us our first look at plot data, probes, multipliers, and more. This can give you an accurate representation of how your circuit will behave. These two SPICE simulation methods sweep a circuit over a defined voltage or frequency range. Now it’s time to ramp up the difficulty with DC sweep and AC sweep analysis. #Ltspice ac source how toWelcome back to our SPICE Simulation Series, Part 3! In Part 2 we showed you how to run a fundamental operating point analysis to simulate current and voltage at a single reference point. SPICE Simulation Part 3: Running Your First DC and AC Sweep Analysis linear inside a given voltage range and fixed saturated limit out of that range.SPICE Simulation Part 3: DC and AC Sweep Analysis If the control voltage isīeyond the range of the look-up table, the output current isĮxtrapolated as a constant current of the last point of the look-upĪs you can see you only need to specify two points in the LUT if you just want a VCCS with an hard limiting characteristics, i.e. The output is linearly interpolated when theĬontrol voltage is between specified points. The output current when the control voltage is equal to the first Here a lookup table is used to specify the transfer function. This is a linearly dependent source specified solely by a constant This circuit element asserts an output current between the nodes n+Īnd n- that depends on the input voltage between nodes nc+ and nc. There are three types of voltage dependent current-source circuit Voltage Dependent Current Source Symbol Names: G, G2 This is the relevant section of the online help (emphasis mine): #Ltspice ac source simulatorNote: the capacitor C1 is there only to avoid an error because the simulator doesn't like node C to be floating. Just use the G circuit element (voltage controlled current source) with a lookup table (LUT) specification:
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