Seyit Ahmet Sis

Large-Signal Performance and Modeling of Intrinsically Switchable Ferroelectric FBARs

This paper presents the large-signal performance of intrinsically switchable ferroelectric thin-film bulk acoustic resonators (FBARs), as well as their modeling procedure. There has been a growing interest in ferroelectric FBARs due to their electric-field-dependent permittivity and electric-field-induced piezoelectricity. Ferroelectric barium-strontium-titanate (BaxSr(1-x)TiO3) FBARs are intrinsically switchable, namely, they have resonances that switch on with the application of a dc-bias voltage. In this paper, the large-signal performance and nonlinear behavior of ferroelectric BST FBARs are investigated. Measurement results show that the device nonlinearity can be reduced by applying higher dc-bias voltages. Moreover, a large-signal model that accurately describes the dc-bias voltage, as well as RF power-dependent performance of BST FBARs is developed. Large-signal simulation results obtained from this model at different bias voltages and RF power levels show good agreement with the measurement results.

Intrinsically switchable, high-Q ferroelectricon-silicon composite film bulk acoustic resonators

This paper presents a voltage-controlled, high-quality factor (Q) composite thin-film bulk acoustic resonator (FBAR) at 1.28 GHz. The composite FBAR consists of a thin layer of barium strontium titanate (BST) that is sandwiched between two electrodes deposited on a silicon-on-insulator (SOI) wafer. The BST layer, which has a strong electrostrictive effect, is used for electromechanical transduction by means of its voltage-induced piezoelectricity. The silicon layer, with its low mechanical loss, increases the Q of the resonator. The composite FBAR presented here exhibits Qs exceeding 800 with a resonance frequency and Q product (f × Q) of 1026 GHz.

Intrinsically switchable interdigitated barium titanate thin film contour mode resonators

This paper presents the design and measurement results of an intrinsically switchable interdigitated contour mode resonator based on barium titanate (BTO) thin films. The device exhibits quality factors of 178 and 152 at series and parallel resonance frequencies of 1.67 and 1.68 GHz, respectively, with the application of a 10 V dc bias. Resonances are turned off without the application of dc bias. This is the first demonstration of an intrinsically switchable interdigitated ferroelectric contour mode resonator.

Intrinsically switchable thin film ferroelectric resonators

This paper presents DC voltage dependent thin film bulk acoustic wave resonators (FBARs) based on ferroelectric barium strontium titanate (BST). The electrostrictive effect in BST film that enables the resonances to switch on and off with dc bias is discussed. Composite BST FBARs that consist of BST, platinum (Pt), silicon (Si), and oxide (SiO2) layers are discussed by comparing with the conventional FBAR structure. For composite FBARs, the BST layer is primarily used for transduction while the Si and SiO2 layers are used to increase the overall quality factor (Q). Measurement results of a composite FBAR show a Q that exceeds 600 at its parallel resonance frequency of 2.169 GHz and an electromechanical coupling coefficient of 0.68%.

Linearity analysis of intrinsically switchable ferroelectric FBAR filters

This paper presents the linearity analysis of intrinsically switchable ferroelectric thin-film bulk acoustic resonator (FBAR) filters for the first time. The FBARs are based on the barium-strontium-titanate (BST) ferroelectric thin-film material. BST FBAR filters composed of two series FBARs and one shunt FBAR are designed, fabricated, and measured. Input-referred third-order intercept point (IIP3) of more than 26 dBm for a 1.6-GHz filter with an insertion loss of 4.1 dB is obtained.

Large signal performance of ferroelectric FBARs

Ferroelectric thin film bulk acoustic wave resonators (FBARs) have been of growing interest due to their electric field dependent properties. Resonators based on the ferroelectric barium strontium titanate (BaxSr(1−x)TiO3, BST) are intrinsically switchable, namely they have resonances that switch on with the application of a dc bias voltage. In this paper, the large signal performance and nonlinear behavior of BST FBARs are investigated. Measurement results show as the dc bias voltage increases, the nonlinear behavior due to high RF input power decreases. For better understanding, measurement results of BST FBARs are fitted to a nonlinear modified Butterworth-Van Dyke (MBVD) model with respect to dc bias voltage and RF input power.

A DC voltage dependent switchable acoustically coupled BAW filter based on BST-on-silicon composite structure

A DC voltage dependent switchable, bulk acoustic wave (BAW) filter is presented in this paper. The filter has a composite structure consisting of a barium strontium titanate (BST) layer sandwiched between top and bottom platinum (Pt) electrodes deposited on silicon (Si) and oxide (SiO2) layers. The electrostrictive property of ferroelectric BST allows for the filter to be turned on and off by applying an electric field across the BST layer. The Si and SiO2 layers are used to increase the overall quality factor and mechanical strength of the structure. When the filter is turned on, the 3 dB bandwidth is 43 MHz at a center frequency of 1.08 GHz. After resonating out the input and output static capacitances of the filter using shunt inductors, the filter exhibits an insertion loss of 8.5 dB with the application of 25 V DC bias. The return loss and out-of-band rejection of the filter are 18 dB and 29 dB, respectively. In its off state, with no DC bias applied, the isolation between input and output ports is 37 dB.

Intrinsically switchable, BST-on-silicon composite FBARs

This paper presents a DC voltage dependent switchable, composite thin film bulk acoustic wave (FBAR) resonator at 1.82 GHz. The resonator consists of barium stronium titanate-on-silicon in which barium stronium titanate (BST) is primarily used for transduction. The electrostrictive property of BST is exploited to turn the resonator on and off by applying a DC voltage. The device exhibits a quality factor of 157 and 301 at its series and parallel resonance frequencies, respectively. The preliminary result of an acoustically coupled thickness mode filter based on BST-on-Silicon structure is also presented. The insertion loss of the filter is 15 dB at 2.03 GHz. When the resonator is turned off (no DC bias), it behaves like a capacitor. This is the first demonstration of a BST-on-Silicon FBAR resonator.

An Intrinsically Switchable, Monolithic BAW Filter Using Ferroelectric BST

This letter presents an intrinsically switchable monolithic filter based on laterally acoustically coupled bulk acoustic wave resonators. The filter is based on a barium strontium titanate-on-silicon (BST-on-Si) composite structure which can be turned on and off by the application of a dc bias. In its off state, the filter provides an isolation of 40 dB. In its on state, the filter exhibits an insertion loss of 7.1 dB and greater than 30 dB of out-of-band rejection. The center frequency and bandwidth of the filter are 748 MHz and 13.8 MHz, respectively. The mechanical quality factor of the coupled resonators is calculated to be 99.

Temperature dependent characteristics of intrinsically switchable ferroelectric composite FBARs

This paper presents temperature dependent characteristics of intrinsically switchable ferroelectric composite FBARs. Ba0.5Sr0.5TiO3 and Si are used to form a composite FBAR. Measurement results show that both series and parallel resonance frequencies decrease with the temperature. The temperature coefficient of frequency is approximately -35 ppm/°C. The variation of quality factor and electromechanical coupling coefficient is less than 6.5% and 6.2% above 20 V bias.