Miniature Common-Mode Rejection Filter in Silicon-Based Integrated Passive Device Technology

In this paper, miniature common-mode rejection filters realized with a silicon-based integrated passive device (IPD) process are presented. The proposed filter is designed with an all-pass response for differential-mode input signals, while it features a bandstop frequency response for common-mode input signals such that the unwanted common-mode noise can be properly rejected within the designated frequency band. Specifically, miniature common-mode rejection filters with narrow or wide rejection bandwidth are implemented in IPD. The narrowband design exhibits a 20-dB common-mode rejection bandwidth from 2.1 to 3.3 GHz while the wideband one features a 20-dB rejection bandwidth from 3.6 to 9.7 GHz. Both filters feature a less than 1.2 dB insertion loss for the differential-mode from dc up to 8.8 GHz, and the circuit size is only 3.71 mm×1.86 mm.