A RF-MEMS based Monolithically Integrated Wide Range Tunable Low Pass Filter for RF Front End Applications

Monolithically integrated, wide tuning range low pass filters have been demonstrated based on electrothermally driven MEMS switches. The integrated system is comprised of copper spiral inductors, polysilicon capacitors and electrothermal MEMS actuators on a single 4.3 times 2.4 mm² chip; the design is optimized for the selection of three commonly used commercial cut-off frequencies: (f_c) at 0.9 GHz, 1.9 GHz and 2.5 GHz. The driving voltage is only 3.7 V and out-of-band attenuation is -39 dB at 3.5 GHz, which is comparable to the state-of-art commercial ceramic filters. As such, this tunable filter and related fabrication technologies are applicable for various RF front end applications.