A miniature LTCC bandpass filter using novel resonators for GPS applications

We present a novel bandpass filter embedded in a low-temperature co-fired ceramic (LTCC) package designed for small size and robustness. Given the three-dimensional packaging capability of the LTCC substrate, the multilayer resonators are integrated into the module - eliminating the need for their discrete versions. The resonators are comprised of high Q spiral inductors that are combined with four layer parallel plate capacitors. The novel topology of placing the capacitor in the centre and two layers below the plane of the inductor allows for simultaneous area and performance optimization. The complete LTCC bandpass filter module measures only 5 mm times 5.4 mm times 0.8 mm. This version of the design utilizes discrete coupling capacitors to minimize size. The simulation results show the filter to have a centre frequency of 1.525 GHz and a bandwidth of 128 MHz. This is believed to be the smallest implementation of a LTCC bandpass filter for GPS applications.