LTspice is a powerful, fast, and free SPICE (Simulation Program with Integrated Circuit Emphasis) simulator software developed by Analog Devices. It is widely used by engineers for simulating analog circuits, mixed-signal circuits, and power electronics. LTspice provides a user-friendly graphical interface for designing circuits, running simulations, and analyzing results. It supports a wide range of components, including resistors, capacitors, inductors, diodes, transistors, and operational amplifiers. Additionally, LTspice allows users to create custom components and models, making it a versatile tool for circuit design and analysis. Feel free to download and install it on your computer LTspice from here.

Users can export circuit digrams from the CircuitsU website as a netlist file (*.net) that can be opened in LTspice for further analysis and simulation.

LTspice is using a modified nodal analysis technique to compute the voltages and currents in the circuit numerically. To simulate a circuit the user create a netlist file that contains a list of components and their connections. Below is a description of some of the basic components that can be inncluded in a netlist file.

1. Independent voltage source

   Vname N+ N- [DC value] [AC value] [transient shape]

2. Independent current source

   Iname N+ N- [DC value] [AC value] [transient shape]

   Both sources can be set can generate waveforms:

   • SIN(offset amplitude freq)

   • PULSE(V1 V2 Tdelay Trise Tfall Ton Tperiod)

   • EXP(...), PWL(...), etc.

3. Resistor

   Rname N1 N2 value

4. Capacitor

   Cname N1 N2 value [IC=initial_voltage]

5. Inductor

   Lame N1 N2 value [IC=initial_current]

6. Voltage-Controlled Voltage Source

   Ename N+ N- NC+ NC- gain

7. Voltage-Controlled Current Source

   Gname N+ N- NC+ NC- transconductance

8. Current-Controlled Voltage Source

   Hname N+ N- Vcontrol gain

9. Current-Controlled Current Source

   Fname N+ N- Vcontrol gain

The ground node is denoted by 0. Since LTspice uses a modified nodal analysis technique to solve the circuit equations, it is important for the circuit to have a ground node. Otherwise, one can get errors such Node XXX is floating or singular matrix.