In this paper, we present a fully integrated 8-bit digital tunable filter module, which enables the center frequency and bandwidth tuning operate in the S band region and featuring a low insertion loss of less than 3.2dB and small size of 3.6 mm by 4.7mm. This tunable filter module is based on a LTCC interposer with the filter circuit directly formed on the front surface using MEMS technology. 6 MEMS switches and CMOS driving IC are mounted on front and reverse sides of the LTCC interposer by flip chip bonding technology. By developed integration technology, we verified prospect for wafer level heterogeneous integration for RF application.