Patent attributes
An integrated variable inductor is achieved by placing a second closed-loop inductor immediately above or below a primary inductor. The closed-loop configuration of the second inductor may be broken on-chip by several ways, including use of a transistor to selectively short together both ends of the second inductor. If one wishes to alter the inherent inductance characteristics of the primary inductor, the transistor coupling both ends of the second inductor is actuated. Thus, a current applied to the primary inductor induces a current in the second inductor by inductive coupling. The second current in the second inductor then alters the impedance of the primary inductor by mutual inductance. Thus, the inductance value of the primary inductor is altered. To remove the influence of the second inductor on the primary inductor, the closed-loop configuration of the second inductor is broken.
