Heterogeneous Integration of 5G and Millimeter-Wave Diplexers with 3D Glass Substrates

Abstract

Package-integrated implementation of highly- miniaturized diplexers is presented for the first time on ultra-thin laminated glass substrates for millimeter-wave (mm-wave) applications in emerging RF front-end modules (FEM). The diplexers are designed using miniaturized, doubly- terminated bandpass filters which cover the 5G new radio (NR) mm-wave bands: n257, n258 and n260. Two different types of filters: hairpin and edge-coupled are modeled, designed and optimized for this non-contiguous diplexer demonstration. Since diplexer is a three-port device, the considerations for optimum RF performance as well as characterization are included in the modeling phase. From the fabrication standpoint, unlike conventional etching processes, panel-scale semi-additive patterning (SAP) process is utilized to form high-precision, fine-feature redistribution layers (RDL) on ultra-thin glass substrates to accurately realize the aforementioned passive components. These diplexers can be integrated with antennas on the top layer of a multilayered 5G module or they can be utilized as integrated passive devices (IPDs). An appropriately sized ground plane is sufficient to isolate the rest of the system from these diplexers, making them ideal for applications such as heterogeneously-integrated packages. The demonstrated diplexers, comprising of 5G NR band filters, exhibit low insertion loss, high stopband rejection, high selectivity, ease-of-integration in packages as well as small footprint. The simulated response of the fabricated diplexers is in excellent agreement with the measured results.