PZT-on-silicon RF-MEMS Lamb wave resonators and filters

H. Yagubizade

    Research output: ThesisPhD Thesis - Research UT, graduation UT

    42 Downloads (Pure)

    Abstract

    Lamb-wave piezoelectric RF-MEMS resonators have demonstrated promising performance, such as low motional impedance and high Q-factor. Lamb-wave resonators are still in the perfectioning state and therefore there is a great demand for further understanding of various issues such as reducing the anchor-loss, spurious mode suppression using various designs and simulation techniques such as finite-element methods. AlN, ZnO and recently PZT thin-films are the prevalent piezoelectric materials utilized in the resonators. Of these, PZT has the highest electromechanical coupling-factor which is a big opportunity to reduce the size of the filters and keep the motional impedance low. PZT suffers from a high feed-through due to its high dielectric permittivity which, as a consequence, drastically reduces the stopband rejection. In this thesis, to overcome this problem, we propose a feed-through cancellation method in the presence of specific grounding resistances (non-zero grounding) at the input- and output-sides, which always exist and prevent perfect grounding. Particularly, these grounding resistances have been considered in the designs. Using the proposed technique, the stopband rejection of the resonator is improved by more than 20 dB. Two different bandpass filter configurations (i.e. mechanically coupled and differentially readout) are presented in this thesis. The mechanically-coupled filter consists of two mechanically-coupled resonators with identical designed wave-length. One resonator is used to actuate the whole coupled structure and the other one is used to pick up the signal. The mechanically-coupled filter is actuated using two differential input signals and on the other side, the output signal is also picked up using a differential readout. As both actuation and readout are done using a differential technique, the feed-through signals trough air and substrate are not eliminated. Therefore, the filter shows a low stopband rejection. To overcome this problem, a new concept of bandpass filter is proposed in this thesis called, differential readout filter. Two different filters at two different resonance frequencies around 380MHz and 700MHz are presented. This technique showed a considerable improvement in the performance of RF-MEMS filters compared to the existing Lamb wave filters. Conventional electromechanical filters are using mechanical and/or electrical couplings, however, this new technique is based on the phase change of two un-coupled resonators below and above their resonances. This technique resolves the design issue associated with high feed-through at high frequencies as well as exploiting piezoelectric materials with high-dielectric constant like PZT.
    Original languageUndefined
    Awarding Institution
    • University of Twente
    Supervisors/Advisors
    • Elwenspoek, Michael Curt, Supervisor
    • Tas, Niels R., Advisor
    Thesis sponsors
    Award date13 Dec 2013
    Place of PublicationEnschede
    Publisher
    Print ISBNs978-90-365-3594-6
    DOIs
    Publication statusPublished - 13 Dec 2013

    Keywords

    • TST-ACTUATORS
    • piezoelectric
    • METIS-302204
    • Band-pass filter
    • IR-89278
    • PZT
    • RF MEMS
    • MEMS
    • EWI-24460

    Cite this

    Yagubizade, H.. / PZT-on-silicon RF-MEMS Lamb wave resonators and filters. Enschede : Universiteit Twente, 2013. 89 p.
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    title = "PZT-on-silicon RF-MEMS Lamb wave resonators and filters",
    abstract = "Lamb-wave piezoelectric RF-MEMS resonators have demonstrated promising performance, such as low motional impedance and high Q-factor. Lamb-wave resonators are still in the perfectioning state and therefore there is a great demand for further understanding of various issues such as reducing the anchor-loss, spurious mode suppression using various designs and simulation techniques such as finite-element methods. AlN, ZnO and recently PZT thin-films are the prevalent piezoelectric materials utilized in the resonators. Of these, PZT has the highest electromechanical coupling-factor which is a big opportunity to reduce the size of the filters and keep the motional impedance low. PZT suffers from a high feed-through due to its high dielectric permittivity which, as a consequence, drastically reduces the stopband rejection. In this thesis, to overcome this problem, we propose a feed-through cancellation method in the presence of specific grounding resistances (non-zero grounding) at the input- and output-sides, which always exist and prevent perfect grounding. Particularly, these grounding resistances have been considered in the designs. Using the proposed technique, the stopband rejection of the resonator is improved by more than 20 dB. Two different bandpass filter configurations (i.e. mechanically coupled and differentially readout) are presented in this thesis. The mechanically-coupled filter consists of two mechanically-coupled resonators with identical designed wave-length. One resonator is used to actuate the whole coupled structure and the other one is used to pick up the signal. The mechanically-coupled filter is actuated using two differential input signals and on the other side, the output signal is also picked up using a differential readout. As both actuation and readout are done using a differential technique, the feed-through signals trough air and substrate are not eliminated. Therefore, the filter shows a low stopband rejection. To overcome this problem, a new concept of bandpass filter is proposed in this thesis called, differential readout filter. Two different filters at two different resonance frequencies around 380MHz and 700MHz are presented. This technique showed a considerable improvement in the performance of RF-MEMS filters compared to the existing Lamb wave filters. Conventional electromechanical filters are using mechanical and/or electrical couplings, however, this new technique is based on the phase change of two un-coupled resonators below and above their resonances. This technique resolves the design issue associated with high feed-through at high frequencies as well as exploiting piezoelectric materials with high-dielectric constant like PZT.",
    keywords = "TST-ACTUATORS, piezoelectric, METIS-302204, Band-pass filter, IR-89278, PZT, RF MEMS, MEMS, EWI-24460",
    author = "H. Yagubizade",
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    PZT-on-silicon RF-MEMS Lamb wave resonators and filters. / Yagubizade, H.

    Enschede : Universiteit Twente, 2013. 89 p.

    Research output: ThesisPhD Thesis - Research UT, graduation UT

    TY - THES

    T1 - PZT-on-silicon RF-MEMS Lamb wave resonators and filters

    AU - Yagubizade, H.

    PY - 2013/12/13

    Y1 - 2013/12/13

    N2 - Lamb-wave piezoelectric RF-MEMS resonators have demonstrated promising performance, such as low motional impedance and high Q-factor. Lamb-wave resonators are still in the perfectioning state and therefore there is a great demand for further understanding of various issues such as reducing the anchor-loss, spurious mode suppression using various designs and simulation techniques such as finite-element methods. AlN, ZnO and recently PZT thin-films are the prevalent piezoelectric materials utilized in the resonators. Of these, PZT has the highest electromechanical coupling-factor which is a big opportunity to reduce the size of the filters and keep the motional impedance low. PZT suffers from a high feed-through due to its high dielectric permittivity which, as a consequence, drastically reduces the stopband rejection. In this thesis, to overcome this problem, we propose a feed-through cancellation method in the presence of specific grounding resistances (non-zero grounding) at the input- and output-sides, which always exist and prevent perfect grounding. Particularly, these grounding resistances have been considered in the designs. Using the proposed technique, the stopband rejection of the resonator is improved by more than 20 dB. Two different bandpass filter configurations (i.e. mechanically coupled and differentially readout) are presented in this thesis. The mechanically-coupled filter consists of two mechanically-coupled resonators with identical designed wave-length. One resonator is used to actuate the whole coupled structure and the other one is used to pick up the signal. The mechanically-coupled filter is actuated using two differential input signals and on the other side, the output signal is also picked up using a differential readout. As both actuation and readout are done using a differential technique, the feed-through signals trough air and substrate are not eliminated. Therefore, the filter shows a low stopband rejection. To overcome this problem, a new concept of bandpass filter is proposed in this thesis called, differential readout filter. Two different filters at two different resonance frequencies around 380MHz and 700MHz are presented. This technique showed a considerable improvement in the performance of RF-MEMS filters compared to the existing Lamb wave filters. Conventional electromechanical filters are using mechanical and/or electrical couplings, however, this new technique is based on the phase change of two un-coupled resonators below and above their resonances. This technique resolves the design issue associated with high feed-through at high frequencies as well as exploiting piezoelectric materials with high-dielectric constant like PZT.

    AB - Lamb-wave piezoelectric RF-MEMS resonators have demonstrated promising performance, such as low motional impedance and high Q-factor. Lamb-wave resonators are still in the perfectioning state and therefore there is a great demand for further understanding of various issues such as reducing the anchor-loss, spurious mode suppression using various designs and simulation techniques such as finite-element methods. AlN, ZnO and recently PZT thin-films are the prevalent piezoelectric materials utilized in the resonators. Of these, PZT has the highest electromechanical coupling-factor which is a big opportunity to reduce the size of the filters and keep the motional impedance low. PZT suffers from a high feed-through due to its high dielectric permittivity which, as a consequence, drastically reduces the stopband rejection. In this thesis, to overcome this problem, we propose a feed-through cancellation method in the presence of specific grounding resistances (non-zero grounding) at the input- and output-sides, which always exist and prevent perfect grounding. Particularly, these grounding resistances have been considered in the designs. Using the proposed technique, the stopband rejection of the resonator is improved by more than 20 dB. Two different bandpass filter configurations (i.e. mechanically coupled and differentially readout) are presented in this thesis. The mechanically-coupled filter consists of two mechanically-coupled resonators with identical designed wave-length. One resonator is used to actuate the whole coupled structure and the other one is used to pick up the signal. The mechanically-coupled filter is actuated using two differential input signals and on the other side, the output signal is also picked up using a differential readout. As both actuation and readout are done using a differential technique, the feed-through signals trough air and substrate are not eliminated. Therefore, the filter shows a low stopband rejection. To overcome this problem, a new concept of bandpass filter is proposed in this thesis called, differential readout filter. Two different filters at two different resonance frequencies around 380MHz and 700MHz are presented. This technique showed a considerable improvement in the performance of RF-MEMS filters compared to the existing Lamb wave filters. Conventional electromechanical filters are using mechanical and/or electrical couplings, however, this new technique is based on the phase change of two un-coupled resonators below and above their resonances. This technique resolves the design issue associated with high feed-through at high frequencies as well as exploiting piezoelectric materials with high-dielectric constant like PZT.

    KW - TST-ACTUATORS

    KW - piezoelectric

    KW - METIS-302204

    KW - Band-pass filter

    KW - IR-89278

    KW - PZT

    KW - RF MEMS

    KW - MEMS

    KW - EWI-24460

    U2 - 10.3990/1.9789036535946

    DO - 10.3990/1.9789036535946

    M3 - PhD Thesis - Research UT, graduation UT

    SN - 978-90-365-3594-6

    PB - Universiteit Twente

    CY - Enschede

    ER -