A fully embedded LTCC multilayer BPF for 3-D integration of 40-GHz radio

Abstract

This paper demonstrates a low loss fully embedded multilayer bandpass filter (BPF) using low-temperature cofired ceramic (LTCC) technology for 3-D integration of 40-GHz multimedia wireless system (MWS) radio. The LTCC filter implemented in a stripline configuration occupies an area of only 5.5 x 2.3 x 0.6 nun including shielding structure and coplanar waveguide (CPW) transitions. The measured insertion loss was as small as 1.9 dB at a center frequency of 41.8 GHz, and the return loss was 12.2 dB including the loss associated with two CPW-to-stripline transitions. This six-layer BPF showed 3-dB bandwidth of 10.5% from 39.6 to 44.0 GHz at a center frequency of 41.8 GHz and suppressed the local oscillator (LO) signal to 20.2 dB at a local oscillator frequency of 38.8 GHz, making it suitable for the 40 GHz MWS applications.