Thin-film Microstrip Line Research Articles

273-GHz 2X Subharmonic Up-Conversion Mixer for System-on-Package Applications

In this paper, a 273-GHz 2X subharmonic passive mixer is proposed for system-on-package applications. The mixer is designed and implemented using thin-film microstrip line on a three-layer package platform. The antiparallel-diode-pair-based mixer up-converts the 135-GHz IF input signal to 273 GHz with a 69-GHz local oscillator. The isolation between the IF and RF ports is achieved by a duplexer. The duplexer is composed of two dual-mode bandpass filters with uniform/nonuniform square ring resonators. The mixer is fabricated and measured, and the measured single-sideband conversion loss is 17.7 dB with an output RF of 270 GHz.

Modeling and simulating the nerve axon as a thin-film microstrip

Since Hodgkin and Huxley described the nerve axon as a cable (H–H model), many efforts have been made to find more approximated transmission line models representing the nerve axon. This paper describes a simple model that represents the nerve axon in two parts: the internodal space as a lossy thin-film microstrip line and the node of Ranvier as an active complex load. The complex load terminating the transmission line is given by the variable impedance of a tunnel diode. First, the internodal space is circuitally analyzed and electromagnetically simulated as a lossy thin-film microstrip line terminated on a complex fixed load. The transmission line circuit theory, the two-port network analysis, and a two-dimensional finite difference time domain method are used for such a task by forcing a strip subatomic metallization. Then, the transfer function of the internodal space, cascaded with the node of Ranvier, is equated to the transfer function of a transmission line section that includes a tunnel diode. This procedure is carried out in order to obtain the diode's variable impedance. The diode was introduced by Nagumo, Arimoto, and Yoshizawa for simulating the nerve axon as an active transmission line. The active transmission line is represented by the FitzHugh simplified H–H model known as the Bonhoeffer–van der Pol model.

Fabrication process of YBCO thin film starting from amorphous film for microstrip line device

Abstract We investigated the process for fabricating YBa2Cu3Oy (YBCO) thin film microstrip lines from amorphous thin films. First, we made amorphous YBCO thin films and then post-annealing was carried out. The amorphous 300-nm-thick YBCO thin films were deposited on a CeO2 buffered r-Al2O3 substrate by pulsed laser deposition. The 50-nm-thick CeO2 buffer layer was made by a facing target sputtering system. We examined the optimal conditions of the post-annealing process by using a two-step crystallization process. The heating rate of the first step was set to 360 K/min until 1023 K, and then the heating rate of the second step was set to 20 K/min until 1073 K. The oxygen pressure was kept to 3000 Pa at 1073 K for 210 min. From the XRD measurement, we observed that the YBCO thin films grew c-axis orientation on the CeO2/r-Al2O3 substrate. Both YBCO and CeO2 φ-scan peaks showed four-fold symmetry and rotated 45 degrees between YBCO (102) grain axis and CeO2 (220) grain axis. The surface roughness, Δφ, and Δφ of YBCO thin films were 35.12 nm, 0.89 degree, and 1.51 degree, respectively. We found these to be the optimal post-annealing conditions in which to make a single phase of YBCO films with Tc of 87 K from amorphous YBCO thin films. Therefore, our process is useful to make high-quality YBCO microstrip lines.

Thin-film transmission lines using cyclic olefin copolymer for millimetre-wave and terahertz integrated circuits

Thin-film microstrip lines and a grounded coplanar waveguide using a cyclic-olefin copolymer as low-loss thin film have been fabricated and characterised up to 220 GHz. Attenuation as low as 0.6 dB/mm around 220 GHz has been measured on a grounded coplanar waveguide with a 22 µm-thick cyclic-olefin copolymer thin film.

Average power handling capability of thin‐film microstrip line under dc‐bias conditions

AbstractAverage power handling capability (APHC) of the thin‐film microstrip line (TFML) under dc‐bias conditions (<1 V) is proposed for the first time. The TFMLs with a 20‐μm‐thick polyimide thin films are fabricated on a low‐resistivity silicon substrate (ρ ≤ 10 Ω cm). Losses and APHC are extracted from the measured S‐parameters up to 50 GHz. This study has also been studied on the different roughness and thermal conductivity of the polyimide film to evaluate the APHC of the dc‐biased TFML. It is believed that the evaluations are useful for the high‐dense microwave monolithic integrated circuits. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:84–87, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25653

The recent developments in knowledge based neural modeling

Abstract Artificial neural networks have been recognized as an important technique in microwave modeling and optimization. This paper gives an overview and recent developments on the knowledge based neural modeling techniques in microwave modeling and design. The knowledge based artificial neural networks are constructed by incorporating the existing knowledge such as empirical formulas, equivalent circuit models and semi-analytical equations in neural network structures. The existing knowledge reduces the complexity of neural network model. This combination requires less training data and has better extrapolation performance than classical neural networks. The advantages of using knowledge based neural network modeling are demonstrated with two microwave modeling applications such as characteristic impedance modeling of thin-film microstrip line and parametric modeling of the differential via holes.

Switched transmission-line type Q-band 4-bit MMIC phase shifter using InGaAs pin diodes

A fully integrated Q-band 4-bit MMIC phase shifter with InGaAs pin diodes has been designed and fabricated. To achieve low insertion loss and good phase shifting characteristics at Q-band frequencies, topology based on a switched transmission line is employed using a thin-film microstrip line structure implemented in the MMIC fabrication process. The fabricated phase shifter has demonstrated good performance such as an insertion loss of less than 6.1 dB in the frequency range 46–49 GHz with a small intrinsic chip size of 2.48×0.87 mm. The results show the best insertion loss characteristic among the switched transmission-line type phase shifters reported at Ka- and Q-band frequencies.

Wide-band continuous-wave terahertz source with a vertically integrated photomixer

A transverse electromagnetic horn antenna is monolithically integrated with a low temperature grown GaAs vertical photodetector on a silicon substrate forming a vertically integrated photomixer. Continuous-wave terahertz radiation is generated at frequencies up to 3.5 THz with a power level reaching 20 nW around 3 THz. Microwave and material concepts allow both qualitative and quantitative explanations of the experimental results. The thin film microstrip line topology has been adapted for active devices by an Au–Au thermocompression layer transfer technique and seems to be a promising generic tool for a new generation of efficient terahertz devices.

A wafer-level 3D packaging structure with Benzocyclobutene as a dielectric for multichip module fabrication

A new wafer-level 3D packaging structure with Benzocyclobutene (BCB) as interlayer dielectrics (ILDs) for multichip module fabrication is proposed for application in the Ku-band wave. The packaging structure consists of two layers of BCB films and three layers of metallized films, in which the monolithic microwave IC (MMIC), thin film resistors, striplines and microstrip lines are integrated. Wet etched cavities fabricated on the silicon substrate are used for mounting active and passive components. BCB layers cover the components and serve as ILDs for interconnections. Gold bumps are used as electric interconnections between different layers, which eliminates the need to prepare vias by costly dry etching and deposition processes. In order to get high-quality BCB films for the subsequent chemical mechanical planarization (CMP) and multilayer metallization processes, the BCB curing profile is optimized and the roughness of the BCB film after the CMP process is kept lower than 10 nm. The thermal, mechanical and electrical properties of the packaging structure are investigated. The thermal resistance can be controlled below 2 °C/W. The average shear strength of the gold bumps on the BCB surface is around 70 N/mm2. The performances of MMIC and interconnection structure at high frequencies are optimized and tested. The S-parameters curves of the packaged MMIC shift slightly showing perfect transmission character. The insertion loss change after the packaging process is less than 1 dB range at the operating frequency and the return loss is less than –8 dB from 10 to 15 GHz.

Broadband InGaAs PIN Traveling-Wave Switch Using a BCB-Based Thin-Film Microstrip Line Structure

This letter describes the design and fabrication of a broadband InGaAs PIN traveling wave switch. A new thin-film microstrip line structure integrated with InGaAs PIN diodes has been used to enhance the switch performance at higher frequencies. The developed InGaAs PIN switch has an insertion loss of less than 3.2 dB and an isolation of greater than 40 dB in a broadband frequency range from 25 to 95 GHz. The BCB-based multi-layer technology effectively reduces the chip size of the fabricated SPDT MMIC switch to 1.05 times 0.58 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . To our knowledge, this is the first InGaAs PIN traveling-wave switch demonstrated up to 95 GHz.

High-Performance Q-Band MMIC Phase Shifters Using InGaAs PIN Diodes

This paper presents the design and implementation of Q-band MMIC phase shifters using InGaAs PIN diodes. The topology using a thin-film microstrip line(TFMS) has been proposed to achieve the desired phase-shift as well as good loss characteristics. Five single-bit MMIC phase shifters have been implemented by using a developed BCB(benzocyclobutene)-based multi-layer fabrication technology. The developed phase shifters have less than 3.4 ㏈ of insertion loss and better than 11 ㏈ of input and output return loss in the frequency range of 43 to 47 ㎓. To the authors’ knowledge, this is the first demonstration of high-performance InGaAs PIN diode-based MMIC phase shifters operating at Q-band frequencies.

A wafer-scale packaging structure with monolithic microwave integrated circuits and passives embedded in a silicon substrate for multichip modules for radio frequency applications

A wafer-level packaging structure with chips and passive components embedded in a silicon substrate for multichip modules (MCM) is proposed for radio frequency (RF) applications. The packaging structure consists of two layers of benzocyclobutene (BCB) films and three layers of metalized films, in which the monolithic microwave ICs (MMICs), thin film resistors, striplines and microstrip lines are integrated. The low resistivity silicon wafer with etched cavities is used as a substrate. The BCB films serve as interlayer dielectrics (ILDs). Wirebonding gold bumps are used as electric interconnections between different layers, which eliminate the need of preparing vias by costly procedures including dry etching, metal sputtering and electroplating. The chemical mechanical planarization (CMP) is used to uncover the gold bumps, and the BCB curing profile is optimized to obtain the appropriate BCB film for CMP process. In this work, the thermal, mechanical, electrical as well as RF properties of the packaging structure are investigated. The packaging thermal resistance can be controlled below 2 °C W−1. The average shear strength of the gold bumps on the BCB surface is about 70 MPa. In addition, a Kelvin test structure is fabricated for resistance testing of the vertical vias. The performances of MMIC and interconnection structure at high frequency are simulated and tested. The testing results reveal that the slight shifting of S-parameter curves of the packaged MMIC indicates perfect transmission characteristics at high frequency. For the transition structure of transmission line, the experimental results are compatible with the simulation results. The insertion loss (S21) is below 0.4 dB from 0 to 40 GHz and the return loss (S11) is less than −20 dB from 0 to 40 GHz. For a low noise amplifier (LNA) chip, the S21 shifting caused by the packaging structure is below 0.5 dB, and S11 is less than −10 dB from 8 GHz to 14 GHz.

Behaviour of CPW and TFMS lines at high temperature for RF applications in sub-45 nm nodes

Coplanar waveguide (CPW) and thin film microstrip (TFMS) lines integrating porous ultra low- k as inter-metal dielectric layers ( k = 2.5) and copper as metal, are for the first time experimentally measured up to 110 GHz and under different temperature conditions, up to 200 °C. The extracted attenuation and propagation coefficients of those transmission lines are compared to simulations performed with MAGWEL software, a frequency domain 3-D Maxwell solver. Based on the characterization results some guidelines related to interconnect design are presented for future applications.

A Millimeter-Wave System-on-Package Technology Using a Thin-Film Substrate With a Flip-Chip Interconnection

In this paper, a system-on-package (SOP) technology using a thin-film substrate with a flip-chip interconnection has been developed for compact and high-performance millimeter-wave (mm-wave) modules. The thin-film substrate consists of Si-bumps, ground-bumps, and multilayer benzocyclobutene (BCB) films on a lossy silicon substrate. The lossy silicon substrate is not only a base plate of the thin-film substrate, but also suppresses the parasitic substrate mode excited in the thin-film substrate. Suppression of the substrate mode was verified with measurement results. The multilayer BCB films and the ground-bumps provide the thin-film substrate with high-performance integrated passives for the SOP capability. A broadband port terminator and a V-band broad-side coupler based on thin-film microstrip (TFMS) circuits were fabricated and characterized as mm-wave integrated passives. The Si-bumps dissipate the heat generated during the operation of flipped chips as well as provide mechanical support. The power dissipation capability of the Si-bumps was confirmed with an analysis of DC-IV characteristics of GaAs pseudomorphic high electron-mobility transistors (PHEMTs) and radio-frequency performances of a V-band power amplifier (PA). In addition, the flip-chip transition between a TFMS line on the thin-film substrate and a coplanar waveguide (CPW) line on a flipped chip was optimized with a compensation network, which consists of a high-impedance and low-impedance TFMS line and a removed ground technique. As an implementation example of the mm-wave SOP technology, a V-band power combining module (PCM) was developed on the thin-film substrate with the flip-chip interconnection. The V-band PCM incorporating two PAs with broadside couplers showed a combining efficiency higher than 78%.

Millimeter‐wave low‐loss transmission lines and resonators in standard 0.18‐μm CMOS technology

AbstractDesign methodologies of CMOS transmission lines (T‐lines) and resonators at millimeter‐wave frequencies are presented. Three different T‐lines including thin film microstrip line, coplanar waveguide, coplanar waveguide with ground, are designed and fabricated in standard 0.18‐μm CMOS technology. After on‐wafer testing to 40 GHz and SLOT de‐embedding calibration, their S‐parameters are extracted and analyzed. To achieve a small size, meandering quarter‐wavelength line resonator and stepped impedance resonator resonating near 30 GHz are designed, with their Q‐factor of 12 and 10.5, respectively. A good agreement between the predicted and measured results has been observed up to 40 GHz. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1579–1582, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23424

79 GHz fully integrated fully differential Si/SiGe HBT amplifier for automotive radar applications

In this work, a fully integrated, fully differential amplifier operating at 79 GHz using a high-speed Si/SiGe heterojunction bipolar technology is presented. This integrated circuit needs a single supply voltage and shows high performance such as high gain, excellent reverse isolation and low power consumption (90 mW at 3 V supply voltage). This result was achieved by using three cascaded cascode amplifiers as well as thin-film microstrip lines and MIM capacitors as reactive elements. In addition, the frequency of operation can be easily adjusted within a wide range by changing the length of the matching network (by using a focused ion beam or an ultrasonic manipulator). Because the measurement of differential ICs operating in the millimeter-wave domain is complex, a simple but efficient layout modification was utilized to easily measure single-ended the differential integrated circuit, also at these high frequencies.

Silicon-on-insulator for high-temperature applications

The silicon-on-insulator (SOI) CMOS technology is one of the best candidates for high-temperature applications due to its low leakage current, steep subthreshold slope, absence of latch-up phenomenon and temperature-resistant threshold voltage. However, the most critical elements for high temperature applications are transmission lines, especially thin-film microstrip lines. In the paper, the impact of high-temperature operation on the RF performance of some SOI circuits is analysed up to 250 degrees C.

Thick and thin film microstripline properties due to polyaniline thin film overlay

Purpose – The purpose of this paper is to compare thick and thin film microstripline response to conducting overlay.Design/methodology/approach – Study changes in transmission and reflection of both thick and thin film microstripline due to overlay of polyaniline (PANI) thin film on stainless steel and silver. PANI was deposited by electropolymerisation method using HCl and H2SO4.Findings – Transmittance of both the thick and thin film microstripline decreases due to the PANI overlay and reflectance increases. Thin film microstripline is more sensitive to the type of conducting overlay than thick film microstripline. PANI deposited on silver is more absorbing than PANI deposited on stainless steel using HCl acid. The overlay makes the response of the microstripline more dispersive.Originality/value – The increase in reflectance and decrease in transmittance can provide information about the type of overlay materials. There is need for newer materials which can replace traditional metals for microstrip com...

Low-Loss Thin Film Microstrip Lines and Filters Based on Magnetorheological Finishing

This paper presents a surface finishing method based on magnetorheological fluid to obtain low-loss high-frequency transmission lines and filters on CMOS-grade silicon. As specimens for the magnetorheological finishing, high- and low- thin film microstrip lines with a 20 m-thick polyimide interface above the ground plane that is patterned on the silicon substrate are evaluated. In all cases, thin film microstrip lines treated with the magnetorheological finishing scheme reveal much lower losses compared to original lines owing to reduced conductor roughness. In addition, low-pass filters with 0.5 dB Chebyshev responses based on high-Z0 and low-Z0 thin film microstrip lines are designed and characterized before and after applying the magnetorheological finishing treatment, exhibiting a roughly 1.0-dB insertion loss improvement for the entire pass band range. The proposed magnetorheological finishing scheme can be applied to smoothen any 3-D high-frequency structures, and it can significantly improve conductor roughness.

Improved circuit model for coplanar‐waveguide to microstrip‐line transition on silicon substrate

AbstractAn improved equivalent circuit model is proposed to accurately characterize a metal via transition, between a finite ground coplanar waveguide (FGCPW) and a finite ground thin film microstrip line (FGTFML), which was fabricated using standard CMOS technology. This circuit model with only a few lumped‐circuit elements is established and optimized to achieve a wide frequency range of operation, i.e., 1.0–30.0 GHz. A via transition circuit is fabricated and the measured results have evidently validated the predicted results derived from our proposed circuit model. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 141–144, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23011