Please submit sites of developers of software for design or analysis of electrical circuits or systems with frequency domain behavior
Even though many products today can be developed and model as digital systems with logic values of 1 or 0, at the lowest level of abstraction electrical circuits have voltage, resistance, power, and frequently frequency. Analog design tools have to do with low frequency circuits such as those found within consumer products. Microwave design tool are used with the portions of systems that are wireless. Power engineering is related to generation and transmission of electrical power or the portions of consumer products that convert 110 volt house wiring current to the internal voltage level of your toys.