Hi! Here is my task: Lowpass filter circuit is given: Input signal to this circuit is: L=36.4mH, C=85.4nF. Calculate and draw output signal. My idea is to: 1) Represent input signal in term of Fourier series (complex form), 2) Calculate transfer function for given circuit (for n-th harmonic), Expression for output signal would be product of Fn of input signal (complex fourier coefficient) and transfer function of circuit. 1) Here is input signal in term of Fourier series (complex form): 2) Here is transfer function for n-th harmonic: (L'=L/2) Output signal is now: First question: what is purpose of second inductor? We don't take into account when calculating transfer function. Second question: If I plot output voltage I calculated, it doesn't match with voltage I got in simulation software. My calculations are related to stady state response of circuit, but it looks like it never goes to steady stade (I would say). What to do in situations like this? Should I use some other method to find transient response (maybe Laplace transform?)?