Band-pass-filter with balun function from IPD technology

Abstract

Band-pass-filters (BPF) and baluns are critical components in the RF channels. Conventional discrete component solutions, like those from LTCC technology, use separate parts for these two functions. As miniaturization is becoming a trend for cost-reduction of wireless products, there is a need to make these devices in smaller form-factors. Integrated passive devices (IPD) technology, using Silicon wafer process techniques, enables smaller form-factor components for RF applications. Typically, compared to discrete LTCC parts, an IPD BPF can be three to five times smaller, and an IPD balun can be two times smaller. We have not only achieved smaller IPDs for these individual function blocks, but have also combined two function-blocks to create a single integrated component, which further reduces the overall size while maintaining good electrical performance. An advanced design methodology has been adopted based on EM simulation for making these IPDs. Good correlation is seen between simulation and test, and the result is that first- run pass has been achieved in the majority of our designs.