Circuit design can be considered an art based on the fundamental concepts we learn in electrical and electronic engineering. Deriving from the Ohm's Law, Kirchoff's Laws the most commonly used equivalent circuits, such as the Thevenin and Norton forms, allows us to simplify many complex circuit blocks, provided that we use reasonable assumptions to simplify each case. All practical components we use as building blocks perform according to design specifications only within a limited frequency range. Except in the case of predominantly digital circuit blocks, passive components such as resistors, capacitors, inductors, and transformers are required as basic elements in circuit design. The first selection criterion for passive components dictates that they should be accurate and stable to ensure proper circuit performance. Second, there are further requirements such as low cost, small size, and surface mounting that must be met to satisfy the broader design specifications.