Equivalent circuit for broadband modelling of on-chip spiral inductors up to millimetre-wave frequencies

A single-stage expandable equivalent circuit is proposed to model an on-chip spiral inductor up to several times its first self-resonant frequency. The equivalent circuit adopts a modified T-section network configuration to achieve an extremely large bandwidth. The modelled results for a series of round spiral inductors fabricated with different turn numbers on InGaAs substrate demonstrate good agreement with measured results over a measurement frequency range up to 50 GHz.