Silicon RF capacitors or thin film capacitors are passive components used to store energy and are an integral part of any RF or wireless circuit. These capacitors operate on the principle of electrostatic capacitance, which is the ability of a material to store an electrical charge in an electrical field. When a voltage is applied to the capacitor, electric charges accumulate on the two metal plates of the capacitor causing an electric field between them. This electric field stores energy, which is used as a current source in an RF circuit.
Silicon RF capacitors offer several advantages over other types of capacitors, such as lower leakage, higher capacitance density, and better frequency response. They are also smaller and lighter than other types of capacitors, making them suitable for portable or mobile applications. In addition, they can be used in high temperature and humidity environments with minimal degradation of performance. Furthermore, their robust nature makes them highly durable with a longer life span.
Despite their advantages, thin film capacitors have relatively high cost compared to other types of capacitors. They also tend to have higher inter-terminal resistance which can limit the high frequency performance of a circuit. Finally, due to their large dissipation factor, thin film capacitors should never be used in DC circuits.