A simple and complete circuit model for the coupling between symmetrical spiral inductors in silicon RF-ICs

Modern RFICs have achieved an impressively high integration level, making cross-coupling effects among different sections of the circuit a potential limit to their functionality. Integrated spiral inductors are a potential source of EM interference. This paper presents a physical equivalent circuit for the accurate wideband modeling of coupling between spiral inductors in CMOS technology, validated by experiments performed on custom test structures. The model proves to be very accurate up to frequencies well above the inductor self-resonance. A simple approximate expression for the mutual inductance is also introduced, useful for the quick estimate of cross talk between different circuit blocks.