Telecommunication applications on-chip spiral transformer for wireless

Passive elements are indispensable in RF systems and are used for matching networks, LC tank circuits, filtering, ... etc. Passive elements can be simply classified into distributed elements including transmission lines and waveguides. As the operating frequency moves into the microwave spectrum, the distributed circuits have a higher Q factor, and thus they are usually used for high-frequency applications. Lumped passive components may be discrete, integrated or embedded. Passive integration technologies allow several passive components to be integrated, either into a substrate (embedded) or onto a substrate (integrated). This paper presents the design and modeling of monolithic square spiral micro-transformer. From the specifications of the flyback converter, we determined the geometric parameters of this micro-transformer. The π-electrical model of this micro-transformer highlights all parasitic effects generated by stacking of different material layers and permits to calculate the technological parameters by using the S-parameters. The important characteristics of a transformer are its inductances values and its parasitic capacitance and resistance, which determine its Q factor and self-resonant frequency.