Integration of microstrip LP and BP filters to multilayer structure based on various LTCC

Abstract

The aim of this paper lies in a design, simulation and integration of microstrip Band-Pass (BP) and Low-Pass (LP) filters into one multilayer package based on LTCC. In this article, we introduce five-section microstrip hairpin BP filter with a centre frequency of 7 GHz and a bandwidth of approx. 2 GHz and microstrip stepped-impedance LP filter with a cut-off frequency of 2.5 GHz. The paper presents simulated and measured results of mentioned filters' scattering parameters (S parameters) based on two different LTCC substrates (GreenTape 9K7X as well as GreenTape 951PX). Accent of this article was to investigate the impact of interlayer vias on microstrip LP filters' performances in the high frequency (HF) area. This paper shows a possibility of how to integrated two different types of filters in one multilayer module without mutual interference in HF area. The developed multilayer structure with integrated microstrip filters should be used as a part of I - Q (In-phase Quadrature) demodulator presented in [1].