A toroidal inductor integrated in a standard CMOS process

This paper presents a toroidal inductor integrated in a standard 0.13 mu m CMOS process. Finite-elements preliminary simulations are provided to prove the validity of the concept. In order to extract fundamental parameters by means of direct calculations, two different and well-known approaches are followed and the results are compared; this comparison provides useful guidelines for the design of the device. A very simple Pi model for low frequencies is derived from 1-port and 2-port measurements, and a good matching with general theory is observed. The coil exhibits an inductance between 0.9 nH and 1.1 nH up to 20 GHz (physical limit for the measurement equipment) and a quality factor approaching 10 at 15 GHz. No self-resonance is observed within the measurement range.