Fully embedded low temperature co-fired ceramics (LTCC) spiral inductors for L-band RF system-in-package (SIP) applications

Abstract

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