Design of miniature multilayer on-package integrated image-reject filters

We present the design, implementation, and characterization of compact on-package integrated multilayer image-reject filters. The filter implemented in a novel lumped-element stripline configuration in a standard low-temperature cofired ceramic technology occupies an area of only 3.8 mm × 2.4 mm × 0.5 mm. A distinct feature of this filter is the optimal use of the parasitics of the lumped-element components to implement other components as an integral part of the filter by novel vertical deployments of planar structures. Measurement data of the prototype indicate 3 dB of insertion loss and 20 dB of return loss at the center frequency of 2.4 GHz, as well as 39-dB attenuation at the image frequency, suitable for Bluetooth applications. This paper demonstrates the feasibility of on-package integration of RF front-end elements where the transceiver module is built and, therefore, significantly reduces the development cost.