Modeling and parameters extraction of InP-based spiral inductors

In RFIC, the high resistivity of InP substrate results in low substrate loss and the improvement of devices and circuits´ performance. At present a few of people do research on modeling of InP-based spiral inductors. The paper has developed an equivalent circuit model of InP-based spiral inductors. Because of the high resistivity of InP substrate, magnetic substrate loss is neglected, and a resistor in series with parasitic capacitance of pads is used in order to account for parasitic substrate resistance. Using a ladder ‘4-element’ structure and a resistor, the model accurately predicts the skin effect and proximity effect of spiral inductor over a wide-frequency range. A capacitor Cf is adopted to represent the coupling capacitance between metal lines and overlap capacitance of two metal layers. The proposed model has been verified by measured results of spiral inductors fabricated on InP substrate and excellent agreement with measurement data up to 35GHz is demonstrated.