Integration of 0/1-Level Packaged RF-MEMS Devices on MCM-D at Millimeter-Wave Frequencies

This paper reports on the development and optimization of 0/1-level packaged coplanar waveguide (CPW) lines and radio-frequency microelectromechanical systems (RF-MEMS) switches up to millimeter-wave frequencies. The 0-level package consists of an on-chip cavity obtained by flip-chip mounting a capping chip over the RF-MEMS device using BenzoCyclobutene (BCB) as the bonding and sealing material. The 0-level coplanar RF feedthroughs are implemented using BCB as the dielectric; gold stud-bumps and thermocompression are used for realizing the 1-level package. The 0-level packaged switches have been flip-chip mounted on a multilayer thin-film interconnect substrate using a high-resistivity Si carrier with embedded passives and substrate cavities. The insertion loss of a single 0/1-level transition is below -0.15 dB at 50 GHz. The measured return loss of a 0/1-level packaged 50-Omega CPW line remains better than -19 dB up to 71 GHz and better than -15 dB up to 90 GHz. It is shown that the leak rate of BCB sealed cavities depends on the BCB width, and leak rates as low as 10^-11 mbar.l/s are measured for large BCB widths (> 800 mum), dropping to 10^-8 mbar.l/s for BCB widths of around 100 mum. Depending on the bonding conditions, shear strengths as high as 150 MPa are achieved.     

Electronically Cold Microwave Artificial Resistors

A Iarge percentage of microwave field-effect transistors (FET's) are shown to act as a broad-band artificial resistor with a resistance of about 25 Omega when their drain is connected to their gate. The resistance appears between the gate-drain lead and the source lead. This resistance can be raised to 50 Omega with its reactive components eliminated over a reasonable bandwidth by using a matching transmission line of the proper impedance and a length near a quarter-wave at midband. An HFET- 1000 constructed in this configuration showed an impedance of 18+-3 Omega over an octave bandwidth, and when transformed with a 30-Omega quarter-wave transmission line produced a resistance of 51+-1 Omega from 8 to 13 GHz. A noise analysis shows that, at some frequencies, some FET's in this configuration will produce artificial resistors with an effective noise temperature as low as 67 K.     

Generation of Microwave Power with a Spark-Gap Cavity

A theory of a lambda/4 transmission line resonator containing a spark gap is developed and parameters such as output spectrum, bandwidth, Q factor, and efficiency are derived. Equivalent circuits incorporating different spark-gap parameters are presented and used for numerical simulation of cavity output. Several fixed and variable frequency cavities are constructed and tested. Typical peak power outputs are 7.2 kW into 50-Omega line at a frequency of 2.1 GHz, and 27 kW into 50-Omega line at a frequency of 1.5 GHz. For proper operation of this device the spark resistance must fall to a value less than the characteristic impedance of the line in a time less than T where f/sub 0/= 1/2T is the required frequency.     

Sharp-Rejection Ultra-Wide Bandstop Filters

In this letter, a modified optimum bandstop filter (BSF) design is presented. Broad stopband and sharp rejection characteristics are achieved by realizing three transmission zeros near the passband edges. Stopband rejection depth and bandwidth can be controlled by the impedances of the configuration. A lossless transmission line model analysis is used to derive design equations. Further, a compact geometry is chosen by replacing the low impedance section with its equivalent dual-high impedance lines, which facilitates convenient folding. To validate the theoretical prediction, a single unit sharp-rejecting prototype BSF having a 20 dB rejection bandwidth of 126% at 1.5 GHz has been fabricated.      

Low RF noise and power loss for ion-implanted Si having an improved implantation process

Very-low-transmission line noise of <0.25 dB at 18 GHz and low power loss /spl les/0.6 dB at 110 GHz have been measured on transmission lines fabricated on proton-implanted Si. In contrast, a standard Si substrate gave much higher noise of 2.5 dB and worse power loss of 5 dB. The good RF integrity of proton-implanted Si results from the high isolation impedance to ground, as analyzed by an equivalent circuit model. The proton implantation is also done after forming the transmission lines at a reduced implantation energy of /spl sim/4 MeV. This enables easier process integration into current VLSI technology.     

High-frequency, low-crosstalk modulator arrays based on FTC polymersystems

A novel electro-optic polymer Furan TetraCyano Indane (FTC) has been utilised in the fabrication of low V_π, high-speed travelling-wave Mach-Zehnder modulator arrays. The modulators were realised with microstrip transmission lines that were optimised resulting in a line loss of 3.64 dB/cm at 40 GHz. Mach-Zehnder modulators based on this design with 1.6 cm interaction length resulted in devices with V_π<5 V and a reasonably fiat frequency response up to 40 GHz. Electrical crosstalk measurements were also conducted on adjacent modulators separated by 400 μm in a modulator array. Without the implementation of any crosstalk reduction techniques, the measurement results indicated a crosstalk level of <-40 dB in the frequency band between 0 and 40 GHz. These impressive results were a consequence of the low dielectric constant of the polymer material at microwave frequencies and of the small lateral dimensions of the microstrip lines     

基于阶梯阻抗发夹谐振器的小型低通滤波器

提出一种基于阶梯阻抗发夹谐振器的小型化微波低通滤波器,该滤波器仅由包含一节微带线的阶梯阻抗发夹谐振器构成。设计结果表明,滤波器3dB通带从DC(Direct Current)到2GHz,回波损耗优于10dB,且插入损耗从DC到1.7GHz时优于0.5dB,带外抑制从2.9～4GHz优于20dB。仿真结果和实验结果吻合良好。这种滤波器尺寸小,易制造,且具有陡峭的截止频率响应特性,可应用于许多微波系统中。     

Wideband and low return loss coplanar strip feed using intermediatemicrostrip

A wideband and low return loss coplanar strip feed has been achieved using an intermediate microstrip line between coax and coplanar strip lines. The measured and calculated return loss are below 13 dB up to 18 GHz. An extended calculation using TDR data shows the return loss below 10 dB up to 30 GHz. This coplanar strip feed is very practical for feeding wideband electro-optic devices which use coplanar strip as the electrodes     

Frequency characteristics of superconductive coaxial lines

By precise manufacturing methods, 1.6-mm 50-Ω superconductive coaxial lines having few impedance irregularities (0.2 to 0.3 Ω) have been produced. Their attenuation constant at 4.2 K shows a smooth gradual increase upto 12.4 GHz in proportion to frequency. The loss at 1 GHz is 0.7 dB/km for the line using tetra fluoroethylene-hexa fluoropropylene (FEP) and 1.6 dB/km for the line using polyethylene (PE).     

Design of Millimeter-Wave Power Divider with Coupled Line

A novel 35GHz 3dB power divider using coupled transmission line is presented. Unlike conventional Wilkinson divider circuit, only the 50 Ω transmission lines are used in the design. The impedance matching can be achieved by coupled transmission line even mode characteristic impedance. The predicated and measured performances agree well.     

220GHz低噪声放大器研究

基于IHP锗硅BiCMOS工艺,研究和实现了两种220 GHz低噪声放大器电路,并将其应用于220 GHz太赫兹无线高速通信收发机电路。一种是220 GHz四级单端共基极低噪声放大电路,每级电路采用了共基极（Common Base, CB）电路结构,利用传输线和金属-绝缘体-金属(Metal-Insulator-Metal, MIM)电容等无源电路元器件构成输入、输出和级间匹配网络。该低噪放电源的电压为1.8 V,功耗为25 mW,在220 GHz频点处实现了16 dB的增益,3 dB带宽达到了27 GHz。另一种是220 GHz四级共射共基差分低噪声放大电路,每级都采用共射共基的电路结构,放大器利用微带传输线和MIM电容构成每级的负载、Marchand-Balun、输入、输出和级间匹配网络等。该低噪放电源的电压为3 V,功耗为234 mW,在224 GHz频点实现了22 dB的增益,3 dB带宽超过6 GHz。这两个低噪声放大器可应用于220 GHz太赫兹无线高速通信收发机电路。     

带有直流偏置的毫米波单刀双掷开关仿真与设计

采用阶跃阻抗传输线和扇形微带短截线,实现了单刀双掷开关的直流偏置,使直流支路与毫米波支路之间的隔离度大于30dB,带宽超过25%,在中心频率30GHz附近回波损耗大于40dB。采用这种直流偏置电路和PIN梁式引线二极管,基于LTCC工艺对单刀双掷开关串联结构进行仿真。设计结果表明在28.5～31.5GHz频率范围内,串联开关的插入损耗小于1.5dB,回波损耗大于15dB,隔离度大于20dB。     

用于无线局域网的双频段低噪声放大器

采用0.18μmCMOS工艺设计并制造了一款新型的应用于无线局域网的双频段低噪声放大器。设计中,通过切换输入电感和负载电感,来使电路分别工作在2.4GHz和5.2GHz频段。在1.8V的电源电压下,在2.4GHz和5.2GHz两个频段上,其增益分别达到了11.5dB和10.2dB,噪声系数分别是3dB和5.1dB。芯片总面积是0.9mm×0.65mm。     

用于40Gb/s光电子器件的新型低成本硅基过渡热沉

提出了一种新型低成本硅基过渡热沉,用以实现高达40Gb/s的高速光电子器件封装. 采用高阻硅衬底作为热沉基底,制作出了0～40GHz范围内传输损耗小于0.165dB/mm的共面波导传输线. 热沉中采用Ta2N薄膜电阻作为负载以实现器件的阻抗匹配,达到了0～40GHz范围内低于-18dB的宽带低反射特性. 和传统硅基平台相比,新型硅基热沉更具有制作工艺简单、导热性能良好等优点. 为了证明其实用性,热沉被应用于高速电吸收调制器的管芯级封装测试,获得了超过33GHz的小信号调制带宽特性,在硅基热沉上首次实现可用于40Gb/s系统的光电子器件.     

X波段阶梯阻抗微带带通滤波器设计

设计了一款X波段的多模带通滤波器,并给出了仿真与实验结果。采用恒定阻抗枝节加载3个阶梯阻抗枝节的方式,构成滤波器的主体;利用表面电流分布图获得影响带内极点分布的枝节参数,通过调整阶梯阻抗枝节参数优化滤波性能。为实现更好的带外抑制能力,滤波器两端各串联一对平行耦合线,在14 GHz引入一个传输零点。实验测试结果显示,所设计滤波器的中心频率为9.76 GHz,带宽为2.4 GHz,30 dB/3 dB矩形系数为1.63,相对带宽为25%,带内插入损耗大部分小于1 dB,大部分回波损耗高于15 dB,与仿真结果较为吻合。     

Wide-band superconducting coplanar delay lines

Two 25-ns high-temperature superconductor delay lines with novel double-spiral meander line structures were fabricated and measured, one based on the conventional coplanar waveguide (CPW) and the other based on the conductor-backed CPW. Compared with other published studies, the performance of the Conductor-backed CPW delay line is among the best in terms of the widest resonance-free band (2-18 GHz), low insertion loss (0.06 dB/ns at 60 K and 10 GHz), small ripple (<1 dB up until 16 GHz), and small dispersion (<2 ns in the variation of group delay between 2-18 GHz). This is also the first coplanar delay line successfully demonstrated without using wire bonding. The reflecting elements in the delay lines were identified through time-domain measurements. Full-wave simulations were performed to compare the double-spiral meander-line structure with conventional double-spiral line, and to identify the geometric factors restricting the bandwidth of the double-spiral meander line.     

High-speed low-voltage modulation with a nonsymmetric Mach-Zehnderinterferometer

The authors demonstrate broadband optical modulation with a Ti:LiNbO₃ nonsymmetric interferometer at microwave frequencies up to 16 GHz. The 3-dB bandwidth of 8.7 GHz is only slightly less than the theoretical limit of 9.6 GHz for a 1-cm-long device. The device uses a 2-μm-thick gold-plated asymmetric stripline electrode, with a characteristic impedance of 40 Ω and ohmic loss of 3 dB/cm at 10 GHz. The DC switching voltage is 6.5 V, and the on/off ratio is -16 dB. Fabrication tolerances in the nonsymmetric interferometer are much less strict than for directional coupler modulators with comparable performance, making this device a better candidate for use in communications systems     

A 23-dBm 60-GHz Distributed Active Transformer in a Silicon Process Technology

In this paper, a distributed active transformer for the operation in the millimeter-wave frequency range is presented. The transformer utilizes stacked coupled wires as opposed to slab inductors to achieve a high coupling factor of k_f=0.8 at 60 GHz. Scalable and compact equivalent-circuit models are used for the transformer design without the need for full-wave electromagnetic simulations. To demonstrate the feasibility of the millimeter-wave transformer, a 200-mW (23 dBm) 60-GHz power amplifier has been implemented in a standard 130-nm SiGe process technology, which, to date, is the highest reported output power in an SiGe process technology at millimeter-wave frequencies. The size of the output transformer is only 160times160 mum² and demonstrates the feasibility of efficient power combining and impedance transformation at millimeter-wave frequencies. The two-stage amplifier has 13 dB of compressed gain and achieves a power-added efficiency of 6.4% while combining the power of eight cascode amplifiers into a differential 100-Omega load. The amplifier supply voltage is 4 V with a quiescent current consumption of 300 mA     

High‐Gain Wideband CMOS Low Noise Amplifier with Two‐Stage Cascode and Simplified Chebyshev Filter

An ultra‐wideband low‐noise amplifier is proposed with operation up to 8.2 GHz. The amplifier is fabricated with a 0.18‐μm CMOS process and adopts a two‐stage cascode architecture and a simplified Chebyshev filter for high gain, wide band, input‐impedance matching, and low noise. The gain of 19.2 dB and minimum noise figure of 3.3 dB are measured over 3.4 to 8.2 GHz while consuming 17.3 mW of power. The Proposed UWB LNA achieves a measured power‐gain bandwidth product of 399.4 GHz.     

A 25–75 GHz Broadband Gilbert-Cell Mixer Using 90-nm CMOS Technology

A compact and broadband 25-75-GHz fully integrated double-balance Gilbert-cell mixer using 90-nm standard mixed-signal/radio frequency (RF) CMOS technology is presented in this letter. A broadband matching network, LC ladder, for Gilbert-cell mixer transconductance stage design is introduced to achieve the flatness of conversion gain and good RF port impedance match over broad bandwidth. This Gilbert-cell mixer exhibits 3plusmn2dB measured conversion gain (to 50-Omega load) from 25 to 75GHz with a compact chip size of 0.30mm². The OP_{1 dB} of the mixer is 1dBm and -4dBm at 40 and 60GHz, respectively. To the best of our knowledge, this monolithic microwave integrated circuit is the highest frequency CMOS Gilbert-cell mixer to date