Miniaturized microwave tunable bandpass filters on high-k LTCC

This paper describes a MEMS tunable bandpass filter, which operates at the K band and features a low insertion loss of -2.79-3.58 dB, a small size of 2.9 mm by 1.5 mm and a wide continuous tuning range of 32%. The tunable filter is based on MEMS-varactors-loaded microstrip resonators and has been directly constructed on a high-k low-temperature-co-fired-ceramics (LTCC) wiring wafer using MEMS-on-LTCC technology. The developed tunable filter was combined with a 90-nm CMOS-based broadband power amplifier to demonstrate a frequency tunable power amplifier module. This tunable power amplifier technique is a first step toward future reconfigurable radio front-end modules up to K-band.