Cascade BAW Filters For Enhanced Near Band Rejection

By Skyworks Solutions, Inc.

Introduction

The SKY33100-360LF is a low cost, easy to use bulk acoustic wave (BAW) band pass filter.

It is housed in an 8-lead QFN 2 x 2 mm package. The filter performs with low insertion loss, good return loss, and excellent near-band rejection. De-embedded s-parameter plots of the insertion loss (lS21l) and the return loss (lS11l) are shown in figure 7. The device is intended for use in the 2.4 GHz WLAN and ISM bands.

This application note demonstrates the design and performance of two cascaded BAW filters with an inter-stage matching circuit between them. The matching topology is used to optimize the inband insertion loss and return loss while enabling enhanced near band rejection.

The optimized design is implemented on a low cost Rogers RO4003C, 8 mil. thick material evaluation board. The measured performance is compared with the ADS (Advanced Design System) RF simulation.

Also included here is the ADS RF simulation of two BAW filters connected in cascade with just a short transmission line (30 mil. long), a minimum separation layout.

Click Here To Download:
•Application Note: Cascade BAW Filters For Enhanced Near Band Rejection