Design of Multilayer Spiral Inductor Resonator Filters

Introduction: The new wireless and mobile communication systems use miniature Radio Frequency (RF) module design technologies to satisfy low-cost and compact size. Theses requirements are critical for some specific application such as bandpass filter, diplexer, and coupler to reduce the cost and size of mobile system. Recent advances in integration technology and device performance paved the way for higher level of System-In-a-Package (SIP). Embedded passives in multilayer substrate are an attractive solution to the implementation of passive components such as RF filter, diplexer and coupler in miniaturized RF module. However, RF bandpass filters are not suitable for SIP due to their relatively large size. Most of today embedded filters in SIP are made on Low Temperature Co-fired Ceramics (LTCC) technology, which eliminates Surface Mount Technology (SMT) and reduces the size of the filter. While LTCC filter can reduce the lateral size due to relatively high dielectric constant, it may not represent the most economical solution. In this paper, we present newly developed bandpass filters using inductor type resonators without any external component. Proposed bandpass filters are designed based on low-cost laminate substrate. Typical design rules for laminate substrate technology are used in the proposed new design for SIP.