A CMOS–MEMS RF-Tunable Bandpass Filter Based on Two High- $Q$ 22-MHz Polysilicon Clamped-Clamped Beam Resonators

Abstract

This letter presents the design, fabrication, and demonstration of a CMOS-MEMS filter based on two high-Q submicrometer-scale clamped-clamped beam resonators with resonance frequency around 22 MHz. The MEMS resonators are fabricated with a 0.35-μm CMOS process and monolithically integrated with an on-chip differential amplifier. The CMOS-MEMS resonator shows high-quality factors of 227 in air conditions and 4400 in a vacuum for a bias voltage of 5 V. In air conditions, the CMOS-MEMS parallel filter presents a programmable bandwidth from 100 to 200 kHz with a < 1-dB ripple. In a vacuum, the filter presents a stop-band attenuation of 37 dB and a shape factor as low as 2.5 for a CMOS-compatible bias voltage of 5 V, demonstrating competitive performance compared with the state of the art of not fully integrated MEMS filters. Index Terms-Bandpass filter, CMOS-MEMS, micromechanical filter, system-on-chip.

Exploiting nonlinearities of micro-machined resonators for filtering applications

“…There has also been active research on the improvement of various aspects of MEMS resonators for frequency filtering applications, such as producing high-Q, high-frequency, and highly selective filters, [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] Both electrically and mechanically coupled resonators have been demonstrated for filter applications. [10][11][12][13][14][15][16][17] Highly tunable filters were studied, where the centre frequency and the bandwidth can be tuned independently.…”

“…[10][11][12][13][14][15][16][17] Highly tunable filters were studied, where the centre frequency and the bandwidth can be tuned independently. [18][19][20][21][22][23] Furthermore, various designs of resonators have been explored, such as ring shaped and rectangular plate resonators, to achieve high-Q high-frequency filter operation. [24][25][26] Parametric resonances, 27 32,33 In this work, we present a technique that combines the hardening and softening responses of The proposed filter consists of two nearly identical laterally actuated clamped-clamped microbeams.…”

“…The outputs of these electrically coupled resonators can be combined using a differential-tosingle ended amplifier 21,35 (similar to the way the LNA is configured in the test setup) and interfaced with integrated circuits for the realization of the proposed filter in practical behavior. In this study, however, we utilize two clamped-clamped beams and rely on the electrothermal tuning of resonance frequencies of the beams to yield the desired filter characteristics.…”

A Coupled Resonator for Highly Tunable and Amplified Mixer/Filter

“…Furthermore, mechanically and electrostatically coupled structures have been successfully used in such communication applications [10][11][12][13][14][15][16][17][18]. Considerable effort has been directed towards achieving a highly selective tunable filter, where the bandwidth and the center frequency can be tuned efficiently [19][20][21][22][23]. Moreover, recent research has been dedicated to achieve filtering and frequency up/down conversion on a single device to broaden the limits of miniaturization and optimize power consumption in portable communication devices [24,25].…”

Electromagnetic Force on Anisotropic-Conducting Film

“…The reported device types include switches, impedance tuners, tunable or reconfigurable filters, phase shifters and MEMS-based antennas [1][2][3][4][5][6][7][8]. However, it is hard to find a report on wireless devices playing a similar role of motor or actuator with continuously moving parts, because the principles based on rotating electric or magnetic field and independent electric and magnetic circuits will never work in RF or microwave frequency.…”