High Performance Microwave Integrated Filters for 5G Applications

Abstract

A 71-76GHz millimeter-wave filter is designed and implemented in a multilayer LTCC module to help attenuate the side spur signal level. The filter is aimed to be embedded in a novel E-band architecture designed at Huawei for millimeter-wave signal communication application. The goal of the filter is to help reduce the third harmonic and fourth harmonic leakage of the LO signal from tripler into the RF channel.Through measurement, for -15dBm received signal power, the 3 rd and 4 th harmonic leakage levels sof the LO signal is around -25dBc, and both of their frequency range are very close to the transmission band. The designed bandpass filter attenuates the 3 rd and 4 th harmonic signal power down to -50dBc with a low filter order and small physical size.Unfortunately, access to the fabricated filter was not possible due to existing political tension between the US government and Huawei. The fabricated filter was not shipped to Ottawa, and as a result, it was not measured.A second bandpass filter operating at 10GHz is fabricated using Rogers4360 substrate for measurement and validation. The measurement results show some deviations with simulation results. The center frequency shifts from 10GHz to 11.25GHz. Through analysis, the milling depth of the fabrication process affects the measurement result. In our test, a 0.243mm milling depth causes the filter center frequency shift to 11.25GHz.iii