Note that these are the same parameters that were defined in Table 1, however, in Multisim you do not have to worry about the complex SPICE syntax. Where .AC initializes an AC Analysis is the sweep type is the number of points in the sweep and are the start and stop frequencies respectively. Note: In SPICE, the command that performs an AC Analysis has the following form: For Linear, is the total number of points spaced evenly from the start to the stop frequency.Ĭontrols the y-axis scaling on the output graph. For Decade/Octave, is the number of points per decade/octave. Its interpretation depends on the Sweep Type. Indicates how the analysis frequency is swept. It must be greater or equal to the starting frequency. It must be greater than zero.Įnding frequency of the frequency sweep. Starting frequency of the frequency sweep. Table 1 describes the Frequency Parameters tab in detail. The additional settings in the Value tab are used for other analyses or for simulating with the instruments. In this exercise you will use the default values, 1V and 0°, respectively. If you want to perform the analysis with specific values for magnitude and phase, double-click the input source, Vin, go to the Value tab and enter values for AC Analysis Magnitude and AC Analysis Phase. The circuit will attenuate frequencies greater that 500 Hz. Experiment with different values to see the circuit’s behavior. Stop the simulation and change the frequency of the AC_VOLTAGE source, Vin.Open the Oscilloscope front panel and run the simulation.Open circuit file butterworth_filter.ms11 located in the Downloads section.You will use AC Analysis to determine its frequency response.Ĭomplete the following steps to configure and run an AC Analysis: This is a fourth-order Butterworth low-pass filter with a cutoff frequency of 500 Hz and a passband gain of 10 (20 dB) this circuit was taken from. Digital components are treated as large resistances to ground.Ĭonsider the circuit shown in Figure 1. AC circuit response is calculated as a function of frequency.Īssumptions: The analysis is applied to an analog circuit, small-signal.