Influence of Etching Trench on Keff2 of Film Bulk Acoustic Resonator

As radio-frequency (RF) communication becomes more ubiquitous globally, film bulk acoustic resonators (FBAR) have attracted great attention for their superior performance. One of the key parameters of an FBAR, the effective electromechanical coupling coefficient (Keff2), has a great influence on the bandwidth of RF filters. In this work, we propose a feasible method to tune the Keff2 of the FBAR by etching the piezoelectric material to form a trench around the active area of the FBAR. The influence of the position of the etching trench on the Keff2 of the FBAR was investigated by 3D finite element modeling and experimental fabricating. Meanwhile, a theoretical electrical model was presented to test and verify the simulated and measured results. The Keff2 of the FBAR tended to be reduced when the distance between the edge of the top electrode and the edge of the trench was increased, but the Q value of the FBAR was not degraded. This work provides a new possibility for tuning the Keff2 of resonators to meet the requirements of different filter bandwidths.

Design and Optimization of the Dual-Mode Lamb Wave Resonator and Dual-Passband Filter

Radio frequency (RF) filters with multiple passbands can meet the needs of miniaturization and integration for 5G communications. This paper reports a dual-mode Lamb wave resonator (DLWR) and a dual-passband filter based on DLWRs. The DLWR consists of a piezoelectric film and two interdigital electrode (IDT) arrays with different thicknesses, which leads to the coexistence of two main modes in the resonator. The resonance frequencies of the two modes can be adjusted separately by changing the thicknesses of the IDTs, which greatly satisfies the requirements of the dual-passband filter. Four DLWRs with different electrode configurations are designed, and the influences of the periodic length and thicknesses of the IDTs on the performance of the DLWR are studied. When the thickness of the piezoelectric layer is 0.75 μm and the two thicknesses of the IDTs are 0.1 μm and 0.3 μm, the resonance frequency of the second main mode is 1.27 GHz higher than the resonance frequency of the first main mode in the DLWR. Furthermore, a dual-passband filter based on the proposed DLWRs is demonstrated with an insertion loss less than 1 dB and a band rejection of about 15 dB. Moreover, two passbands at 2.45 GHz and 3.88 GHz with bandwidths of 66 MHz and 112 MHz, respectively, are achieved. The presented DLWR shows a potential application that can be used to obtain RF filters with adjustable dual passbands.

Magneto-electric nano-composite for analog tunable radio frequency filters

<p><b>The emerging field of magnetoelectric electronics opens significant opportunities for the next generation of sensors and wireless devices. A key feature of magneto-electric materials is the coupling between their magnetic and electronic properties that enables a voltage to be induced by a magnetic field, or a magnetic response to be induced by an electric field. This occurs in ferroelectric and ferromagnetic bi-layers. It also intrinsically occurs in multiferroics but obtaining a large room temperature magneto-electric effect with such materials can be challenging.</b></p> <p>The National Isotope Centre, part of the Institute of Geological and Nuclear Sciences (GNS Science), has been working with Victoria University of Wellington (VUW) on a novel idea to use low energy ion implantation to create ferromagnetic nanoparticles on ferroelectric and multiferroic thin films to create a magneto-electric nanoparticle composite thin film. They demonstrated the viability of magneto-electric nano-composites in two early stage proofs-ofconcept: a tunable radio frequency filter for wireless systems and a zero-power magnetometer measuring small electrical signals. The aim of this project is to assess the range of fields that this composite could have applications in, identifying the most promising of those fields and assessing the most promising applications in that field. Furthermore, this project also seeks out potential partners in New Zealand and a business case was subsequently prepared, which will be used to apply for government funding to pursue research on the technology, and to begin its commercialisation.</p> <p>In this study nine fields were found to potentially benefit from the use of this technology. They were analysed and compared, using preliminary market validation, resulting in the decision to investigate further the tunable radio frequency (RF) filter market, which is projected at US$13 billion by 2020. RF filters are designed using an original method patented in the 1930s allowing a filter to address only one frequency. As a result, a device must integrate as many filters as frequencies it needs to use, which could be more than 50 for a recent smartphone. A tunable RF filter with a 20% tunability could disrupt this market by providing a huge gain of space, weight, and power efficiency. The RF market is also promising because of the wireless trend, which is occurring all over the world where everything is progressively connected to the what is called the ‘Internet of Things’ – the most important market for the next generation of interconnected electronics. During a year of literature review, interviews and participation at international fairs, the research team has built a value proposition case, a technology review, a market and competitive analysis, an intellectual property assessment and a commercialisation pathway, which are detailed in this project report.</p> <p>The initial Smart Idea funding from the government has now ended and, if the project is to be kept alive, it needs to produce a quick-to-market application to unlock new credits. This report proposes a structured roadmap for several applications, starting with a tunable RF filter prototype for underwater communication. This has been progressed by GNS Science, embarking on a grant application during this writing. If granted, this funding could open the way to make New Zealand a champion in tunable RF filters and a research and development (R&D) hub for next generation nano-electronics.</p>

Magneto-electric nano-composite for analog tunable radio frequency filters

<p><b>The emerging field of magnetoelectric electronics opens significant opportunities for the next generation of sensors and wireless devices. A key feature of magneto-electric materials is the coupling between their magnetic and electronic properties that enables a voltage to be induced by a magnetic field, or a magnetic response to be induced by an electric field. This occurs in ferroelectric and ferromagnetic bi-layers. It also intrinsically occurs in multiferroics but obtaining a large room temperature magneto-electric effect with such materials can be challenging.</b></p> <p>The National Isotope Centre, part of the Institute of Geological and Nuclear Sciences (GNS Science), has been working with Victoria University of Wellington (VUW) on a novel idea to use low energy ion implantation to create ferromagnetic nanoparticles on ferroelectric and multiferroic thin films to create a magneto-electric nanoparticle composite thin film. They demonstrated the viability of magneto-electric nano-composites in two early stage proofs-ofconcept: a tunable radio frequency filter for wireless systems and a zero-power magnetometer measuring small electrical signals. The aim of this project is to assess the range of fields that this composite could have applications in, identifying the most promising of those fields and assessing the most promising applications in that field. Furthermore, this project also seeks out potential partners in New Zealand and a business case was subsequently prepared, which will be used to apply for government funding to pursue research on the technology, and to begin its commercialisation.</p> <p>In this study nine fields were found to potentially benefit from the use of this technology. They were analysed and compared, using preliminary market validation, resulting in the decision to investigate further the tunable radio frequency (RF) filter market, which is projected at US$13 billion by 2020. RF filters are designed using an original method patented in the 1930s allowing a filter to address only one frequency. As a result, a device must integrate as many filters as frequencies it needs to use, which could be more than 50 for a recent smartphone. A tunable RF filter with a 20% tunability could disrupt this market by providing a huge gain of space, weight, and power efficiency. The RF market is also promising because of the wireless trend, which is occurring all over the world where everything is progressively connected to the what is called the ‘Internet of Things’ – the most important market for the next generation of interconnected electronics. During a year of literature review, interviews and participation at international fairs, the research team has built a value proposition case, a technology review, a market and competitive analysis, an intellectual property assessment and a commercialisation pathway, which are detailed in this project report.</p> <p>The initial Smart Idea funding from the government has now ended and, if the project is to be kept alive, it needs to produce a quick-to-market application to unlock new credits. This report proposes a structured roadmap for several applications, starting with a tunable RF filter prototype for underwater communication. This has been progressed by GNS Science, embarking on a grant application during this writing. If granted, this funding could open the way to make New Zealand a champion in tunable RF filters and a research and development (R&D) hub for next generation nano-electronics.</p>

High performance photonic microwave filters based on a 50GHz FSR optical soliton crystal Kerr micro-comb

We demonstrate a photonic radio frequency (RF) transversal filter based on an integrated optical micro-comb source featuring a record low free spectral range of 49 GHz yielding 80 micro-comb lines across the C-band. This record-high number of taps, or wavelengths for the transversal filter results in significantly increased performance including a QRF factor more than four times higher than previous results. Further, by employing both positive and negative taps, an improved out-of-band rejection of up to 48.9 dB is demonstrated using Gaussian apodization, together with a tunable centre frequency covering the RF spectra range, with a widely tunable 3-dB bandwidth and versatile dynamically adjustable filter shapes. Our experimental results match well with theory, showing that our transversal filter is a competitive solution to implement advanced adaptive RF filters with broad operational bandwidths, high frequency selectivity, high reconfigurability, and potentially reduced cost and footprint. This approach is promising for applications in modern radar and communications systems.

Microwave photonic filters using optical to microwave frequency bandwidth translation with Kerr soliton crystal micro-combs

We demonstrate high-resolution photonic RF filters using an RF bandwidth scaling approach based on integrated Kerr optical micro-combs. By employing both an active nonlinear micro-ring resonator (MRR) as a high-quality micro-comb source and a passive high-Q MRR to slice the shaped comb, a large RF instantaneous bandwidth of 4.64 GHz and a high resolution of 117 MHz are achieved, together with a broad RF operation band covering 3.28 to 19.4 GHz (L to Ku bands) using thermal tuning. We achieve programmable RF transfer functions including binary-coded notch filters and RF equalizing filters with reconfigurable slopes. Our approach is an attractive solution for high performance RF spectral shaping with high performance and flexibility.