L-band RF characteristics of LTCC embedded spiral inductors

Fully embedded structures of spiral inductors in a low loss dielectric multi-layer have been designed and fabricated using a low temperature co-fired ceramics (LTCC) technology for three-dimensional RF module integrations. The line width/space and the number of spiral layers of the embedded inductors were optimized for high Q-factor, high self-resonant frequency (SRF), process easiness, and compact size. With a same dimension and number of turns, embedded multi-layer spiral inductors reveal better performance in terms of Q-factor, SRF and the effective inductance than embedded planar spiral inductors. The optimized multi-layer spiral inductor shows maximum Q-factor of 56 and SRF of 3.6 GHz for 6.6 nH effective inductance at Q/sub max/, while planar spiral inductors have maximum Q-factor of 49 and SRF of 3.0 GHz even for 5.8 nH.