Characterization of On-Chip Multiport Inductors for Small-Area RF Circuits

This paper proposes a novel calculation method to derive self and mutual components of each segment in multiport inductors. In the proposed method, a set of S-parameters of the multiport inductor is mathematically decomposed into several matrices, which express self and mutual effects of each segment in the inductor. Due to this mathematics-based method, the multiport inductor can be characterized without numerical extractions. In this paper, a small-area distributed amplifier (DA) utilizing five-port inductors is also demonstrated as an application of the proposed analysis method. In the experimental results using a 0.18-mum CMOS process, the three-stage DA utilizing two five-port inductors to replace eight two-port inductors shows that the multiport inductor can successfully reduce layout area.