Frequency domain analysis is very important to know more about any system/ circuit or transfer function that we deal with. And the first thought comes to our mind about frequency domain analysis is “Bode plot“. Bode plot is a combination plot of magnitude and phase difference of output vs. input of a cosine wave of single frequency, when it is applied to a circuit.
Each of these cosine wave (signal) are applied once at a time and the frequency (in Hz or rad/sec) is increased in linear order (called chirp). All the while the amplitude of sine wave is kept constant (at say 1V_peak). While the frequency can be increased in small steps (1Hz/ sec), the time required to complete the entire frequency range can be quite big. Hence, it is preferred to choose 20 frequencies/ decade. For example, I had chosen 05Hz, 1Hz, 1.5Hz, 2Hz, 2.5Hz… 10Hz.