#The ltspice iv simulator pdf software
The Software simulates noise that is intrinsic to components, using the “Noise” type simulation. It is important to clarify this aspect of LTspice. We can see that the filter response is flat until reaching the cut-off frequency:įc=12*R*C=12*1000*10-6=159,16 Hz Simulating noise and filters There are two lines, the continuous one corresponds to the magnitude (dB) while the discontinuous corresponds to the phase. Scale, start and stop frequency, as well as the number of points to calculate are necessary for the definition of an AC analysis.Īfter running the simulation, we can plot the output level relative to the input, i.e. Many parameters can be configured in a voltage source at LTspice, but amplitude is enough for our purposes. We are going to see its capabilities with a simple low-pass filter:įor any AC analysis, we need to define one AC source.
One of the most interesting analyses that LTspice can perform is the frequency analysis, also known as AC analysis. The type of components and their location varies depending on the type of noise to attenuate. To be really effective against interferences, the design of filters need to consider both types of noise. The current generated by the voltage supply V1 will circulate through R1 and then it will go back to the source, so to ground or the reference voltage. The following circuit is simple, but it will serve to explain the two types of noise.
every current need to go back to its source. Common mode and differential noiseīefore designing a good filter, we need to know what kind of noise can be present in a circuit.Īccording to Kirchoff’s laws, the total current at an electric node is zero, i.e.
#The ltspice iv simulator pdf how to
In this article, we will review the different types of noise that are present in a circuit, as well as how to have an accurate simulation of an EMC filter with LTspice. Parasitics play a key role in filtering since they can provoke the opposite effect and amplify the noise. To obtain accurate results in the simulations, as close as possible as under a real environment, real effects need to be taken into account. In particular, Electromagnetic Compatibility (EMC) filters are used to reduce noise and interferences. Filters are critical elements in a circuit for many applications. Besides, complex analyses such as Worst Case Analysis, frequency response, or noise analysis, among others, can be completed in a short time. It can perform simple simulations to verify the functionality of a new design. LTspice is a very powerful tool for simulating electronic circuits. This article has been firstly publicated in allaboutcircuits.