Design and analysis of symmetric dual-layer spiral inductors for RF integrated circuits

An area efficient and symmetric dual-layer spiral inductor structure is proposed and evaluated in comparison with the conventional single-layer spiral inductors. Measurements show that, for a given silicon area, the dual-layer inductor provides nearly 4 time the inductance of the single-layer inductor, while the quality factor is up to 2 times higher. For the same amount of inductance the dual-layer inductors show comparable to higher quality factor depends on frequency of operation. This paper demonstrates that, contrary to the common understanding the dual-layer can be more useful for the RF integrated circuits than the conventional single-layered spiral inductors from the aspects of area efficiency and quality factor The proposed dual-layer inductor can also be used as a high-frequency choke.