Inductors are not commonly used in integrated circuits (ICs) due to several technical challenges and limitations inherent in their fabrication and integration into semiconductor processes. One primary reason is the difficulty in fabricating small, high-quality inductors using standard semiconductor manufacturing techniques. IC fabrication processes are optimized for creating intricate patterns of transistors, resistors, and capacitors on silicon substrates using photolithography and deposition methods. These processes are not well-suited for accurately producing the fine wire coils and magnetic cores necessary for inductors.
Moreover, inductors tend to occupy a larger area compared to other passive components like resistors and capacitors, which can limit the integration density and complexity of IC designs. The physical size and the associated parasitic effects of inductors, such as mutual inductance and magnetic coupling, can introduce unwanted electrical interference and degrade the performance of nearby circuit elements in ICs.
In DC circuits, capacitors are preferred over inductors due to their ability to store and release electrical energy in the form of an electric field, which is more easily integrated and controlled within IC designs. Capacitors can filter out noise, stabilize voltage levels, and provide coupling and decoupling functions without the complexities and size limitations associated with inductors. Additionally, inductors are not commonly used in VLSI (Very Large Scale Integration) design because the design process focuses on minimizing size, power consumption, and maximizing speed, which capacitors are better suited for.
Overall, while inductors play critical roles in analog circuits and power electronics outside of ICs, their implementation within integrated circuits is limited by fabrication challenges, size constraints, and the availability of alternative components like capacitors that offer more practical and efficient solutions for most IC applications.