Miniaturized Lumped-Element LTCC Filter With Spurious Spikes Suppressed Vertically-Interdigital-Capacitors

A miniaturized lumped-element 10-layer low temperature co-fired ceramic (LTCC) filter is proposed for the extremely low center-frequency of 60 MHz. The miniaturization is achieved by using spiral inductors with high-impedance lines and spurious spikes suppressed vertically-interdigital-capacitors (SVICs). By interconnecting the open ends of interval fingers with vertical vias, capacitance increment and spurious spikes suppression of vertically-interdigital-capacitor (VIC) are achieved without Q-factor degradation. The proposed filter has the smallest reported size of only 0.004 ×0.004 ×0.0004 λg. Furthermore, comparisons and discussions are also implemented.