AC analysis with multiple sources PUBLIC

A demonstration of how to run an AC analysis of a circuit with two AC sources.

A demonstration of how to run an AC analysis of a circuit with two AC sources.

The circuit shown has two input sources, Vac1 feeding 1V into a 1st order lowpass filter section with the a 1kHz cutoff frequency and Vac2 feeding 10V into a 1st order highpass filter section with the same cutoff frequency.

The outputs of each section are summed by Vsum1.

Simulate > Frequency Domain

Note that the 'Input' is given as Vac1, the input to the lowpass section.

Run Frequency Domain Simulation

A Bode plot of V(out) is plotted and this is the same as the Bode plot of the output of the lowpass section at N1.

The Bode plot of the output at N2 shows zero phase and the magnitude is off the bottom of the plot (log of 0 is -infinity).

If the 'Input' is changed to Vac2 then the Bode plots will show that the output is the same as the output of the highpass section at N2 and the output at N1 shows zero phase and the magnitude is off the bottom of the plot.

Note however, that the scale of magnitude response for Vac2 is the same for Vac1. This is because the magnitude of a Bode plot is the ratio of the output divided by the input.