Arian Rahimi

A surface micromachined broadband millimeter-wave filter using quarter-mode substrate integrated waveguide loaded with complementary split ring resonator

A millimeter-wave bandpass filter (BPF) using complementary split-ring resonator (CSRR) loaded quarter-mode substrate integrated waveguide (QMSIW) cavities is presented in this work. The CSRR-loaded QMSIW cavity resonates below the original QMSIW resonance frequency, which further reduces the size with respect to its SIW counterpart. The reduced quality factor Q of the cavity makes it useful for BPFs with broad fractional bandwidth (FBW). A micromachined 4th order Chebyshev BPF is demonstrated at the unlicensed 57 GHz to 64 GHz frequency band. A FBW of more than 11.6% with an in-band return loss of better than 15 dB, and an insertion loss of less than 2.5 dB are obtained.

Cylindrical radial superlattice conductors for low loss microwave components

Theory and experimental demonstration of a cylindrical radial superlattice (CRS) conductor composed of alternating nanoscopic non-ferromagnetic/ferromagnetic metal layers are presented with focus on low conductor loss in a K-band microwave spectrum. The dynamic frequency response of the ferromagnetic thin films has been extracted using the Landau-Lifshitz-Gilbert equation which shows a negative magnetic permeability value in the frequencies above its ferromagnetic resonance. The reduction of the conductor loss results from the eddy current canceling (ECC) effect in the CRS conductors, where the negative-permeability ferromagnetic and positive-permeability non-ferromagnetic metal layers produce a zero effective permeability, resulting in virtually infinite skin depth at the targeted frequency. The closed and uniform boundary conditions inherent in the radial shape conductors preclude discontinuity effects occurring at the edges of the planar superlattice conductor and end up with a more effective ECC effec...

Study on Cu/Ni Nano Superlattice Conductors for Reduced RF Loss

We report on Cu/Ni paired superlattice conductors featuring reduced radio frequency (RF) loss based on eddy current cancelling (ECC). Also, the effects of the width and the individual layer thickness of the superlattice conductors have been studied for improved RF performance. The usage of Ni as the ferromagnetic material in the non-ferromagnetic/ferromagnetic superlattice structure is advantageous as it has a high contrast between the in-plane and out-of-plane magnetic coercivity fields making it suitable for effective thin film superlattice ECC, is abundant, and does not require a stoichiometric control of composition as other alloy magnetic materials do. Nis negative permeability is also able to effectively cancel out the positive permeability of copper in the frequency of interest. A transmission line consisting of 10superlattice Cu/Ni layers, with each layer being of 150 nm/25 nm totaling 1.75 μm shows the same resistance value as one consisting of 10 Cu/Ni layers with each being 600 nm/100 nm totaling 7 μm thick at 13 GHz, revealing 75% conductor volume reduction. Experimental results show more than three times improvement in the figure of merit defined as frequency/effective resistivity, compared with other state-of-the-art devices.

Through Glass Via (TGV) disc loaded monopole antennas for millimeter-wave wireless interposer communication

A monopole antenna loaded with a circular disc is integrated on a glass interposer layer for millimeter-wave wireless communication applications. A Through Glass Via (TGV) is used as a main radiator and the circular disc is for a impedance matching. An omnidirectional radiation pattern formed by the monopole antenna allows in-plane wireless communication whose distance is much larger than 1cm. This can solve problems such as cross talk and time delay caused by the conventional wire bonding approach. A 77 GHz (W-band) antenna is designed and fabricated as a prototype on a glass substrate. The simulated peak gain of the antenna is 1.23 dBi. Also, as this antenna concept is scalable, the same architecture has been exercised for a 5.8 GHz industrial, scientific and medical, ISM band application. The design, fabrication, and characterization are detailed. The measured results of the return loss and radiation pattern agree well with the simulation results.

Flexible Liquid Crystal Polymer based complementary split ring resonator loaded quarter mode substrate integrated waveguide filters for compact and wearable broadband RF applications

In this paper the flexible Liquid Crystal Polymer (LCP) substrate is used to implement broadband wearable/foldable conformal bandpass filters that use compact cavity resonators working under the principle of quarter mode substrate integrated waveguide (QMSIW), which features a 75% size reduction with respect to the conventional substrate integrated waveguide (SIW) counterpart. Further size reduction is realized with the use of a complementary split ring resonator (CSRR) metamaterial unit cell integrated with the QMSIW architecture. The resulting CSRR-loaded QMSIW cavity has its main resonance frequency below the quasi-TE0.5,0,0.5 resonance mode of the original QMSIW cavity due to the evanescent wave amplification phenomenon with CSRR loading. A low temperature surface micromachining process on the LCP and mechanical drilling of via holes are used for fabrication. The realized CSRR-loaded QMSIW cavity features a moderate quality factor (Q) that makes it useful for the design of bandpass filters with much broader fractional bandwidth (FBW) when compared to those using conventional SIW cavities. A 2nd order and a 3rd order surface micromachined Chebyshev BPFs are demonstrated for operation at a center frequency of 25.5 GHz. More than 11% FBW with an in-band return loss of better than 20 dB and an insertion loss of less than 1.5 dB, including transitions, are obtained for both filters. Theoretical analysis of the working principle is explained. Measured results are in good agreement with the 3D full wave structure simulations.

Integrated low loss RF passive components on glass interposer technology

In this work, a glass interposer layer has been used as the low loss structural medium for the implementation of high performance integrated RF passive components. High frequency characterization of the glass interposer layer, and the design, fabrication, and characterization of glass interposer integrated bandpass filters are detailed. Ring resonators with grounded coplanar waveguide (G-CPW) feedings and different dimensions are used to characterize the glass interposer substrates up to 50 GHz where the relative permittivity and loss tangent could be extracted. Half-mode substrate integrated waveguide (HMSIW) architecture loaded with the complementary split ring resonators (CSRR) is chosen to realize compact resonators and bandpass filters for two ISM bands of 2.4 GHz and 5.8 GHz. Through glass via (TGV) structures are fabricated using a laser fusion process on a glass interposer from Corning Inc. Surface micromachining techniques are used for the fabrication of the proposed devices. The measurement results show less than 1.8 dB insertion loss for the 2-pole bandpass filters in 2.4 and 5.8 GHz bands.

Hybrid cylindrical radial superlattice conductor-based air-lifted RF inductors with ultra-high quality factor for UWB and K-bands

This paper reports the state-of-the-art air-lifted radio frequency (RF) inductors made of hybrid cylindrical radial superlattice (h-CRS) conductors with a gold core featuring ultra-high quality factor (Q-factor) in ultra wideband (UWB) and K-bands. A CRS conductor is made of paired Cu/NiFe layers with a thickness of each pair of 150 nm/25 nm, respectively, using a DC/RF sputtering thin film deposition process. The negative permeability of NiFe thin films above their ferromagnetic resonance frequency is used to cancel the eddy currents inside conductors and reduce the conductor loss in Ku and K-bands. The directional thin film deposition aspect of the used fabrication method for the CRS conductors results in a hybrid conductor structure comprising both solid and multi-layer superlattice parts leading to dual-band high-Q characteristics in UWB and K bands. The intrinsic radial shape of the utilized CRS conductors with the uniform and closed boundaries make them superior for the super compact RF low loss conductors. In result of using CRS conductors with ultra-thin layers and the air-lifted structure with suppressed dielectric losses, a record-breaking Q-factor of greater than 80 at 20 GHz is achieved for 1.8 nH inductors.

Magnetically tunable nano-superlattice metaconductors for RF applications

A nanomachined ferromagnetic and non-ferromagnetic superlattice approach is used for tunable radio frequency (RF) conductors, where the current flow profile through the volume of the conductor is magnetically manipulated and so is the RF resistance. The magnetically tunable nano-superlattice conductors with a variable ohmic resistance in GHz range are successfully demonstrated. The realized superlattice conductor consists of an alternating 20 layers of Cu/Ni and Cu/NiFe thin films with a thickness of each pair of 150 nm/25 nm where 150 nm is a few times smaller than the skin depth of Cu in the frequency range of interest. As a total multi-layer conductors thickness of 1.75 μm has shown to have a reverse RF resistance performance as a function of frequency compared to its solid Cu counterpart with the same thickness, we call this artificial conductor as the “metaconductor”. In 10 MHz - 20 GHz frequency range, the metaconductors show an increased ohmic resistance in less than 10 GHz, but a reduced ohmic resistance in greater than 10 GHz range as “low loss conductors” in especially Ku and K bands. The RF frequency showing maximum resistance is magnetically tunable by more than 700 % (1 GHz ~ 7 GHz).

In-Substrate Resonators and Bandpass Filters with Improved Insertion Loss in K-Band Utilizing Low Loss Glass Interposer Technology and Superlattice Conductors

In this work, we report on in-substrate passive components using a high performance glass interposer and through glass via (TGV) technology and a multi-layer superlattice conductor architecture. Minimal RF loss is achieved using low dielectric loss glass substrates and superlattice conductors featuring skin effect suppression. Half mode substrate integrated waveguide (HMSIW) resonators and two-pole bandpass filters, embedded inside a glass interposer substrate, are used as test vehicles for the demonstration of insertion loss improvement in K-band. The utilized conductor is made of 20 layers of Cu/NiFe with each pair of 360 nm/30 nm, respectively, where NiFe layers with negative permeability in frequency range of interest are used for eddy current cancelling and improving the conductor loss. Control devices using the same glass substrate and conductor made of pure copper are fabricated for comparison purposes. The glass interposer substrate (SGW3, Corning Incorporated) has a thickness of 0.13 mm and the TGVs with a diameter of 0.08 mm. Up to 0.3 dB reduction in the insertion loss is achieved by using the proposed superlattice approach on glass substrates.

Cu/Co metaconductor based high signal integrity transmission lines for millimeter wave applications

This work reports copper/cobalt (Cu/Co) metaconductor based coplanar waveguide (CPW) transmission lines, featuring excellent signal integrity at K-bands and millimeter wave frequencies such as low conductor loss, reduced signal dispersion, and low noise figure. CPW transmission lines consisting of 10 pairs of Cu/Co thin film metaconductors with each layer thickness of 150 nm/25 nm, respectively, have been designed, fabricated and characterized. Experimental results show an RF resistance reduction of up to 50 % (Max.) in 7 GHz–32 GHz, 25.5 % delay performance improvement, and 30 % thermal noise voltage reduction compared with reference copper based CPWs. Compared with devices from other literatures, the presented device shows the best signal integrity performance in Ku, K, and Ka bands.