LTCC layer-to-layer misalignment tolerant helical inductors

The inductance of a helical inductor is related to the self inductance of each line segment and mutual inductance between line segments. As mutual inductance is dependent on the distance between coupled metal lines within helical inductors, mutual inductance in traditional straight line helical inductors is susceptible to layer-to-layer misalignment during fabrication if two coupled lines are located at different substrate layers. Two types of misalignment tolerant helical inductors (MaTHI) are proposed to alleviate the effect of misalignment on mutual inductance. Circuit model is also proposed to describe their mechanism. Their performance is verified and compared using helical inductors based resonator circuits. Simulation and measurement results show that two types of proposed MaTHI have more stable performance than traditional stacked helical inductor under misalignment.