交错并联Boost PFC升压电感研究

本文分析了在电感电流断续模式下，交错并联的两个Boost PFC电路采用分立电感与耦合电感的工作过程。相对于分立电感，采用耦合电感的Boost PFC电路，存在电感峰值电流大，输入电流谐波分量高，功率因数低等问题。针对这些问题，采用了一种新颖的集成电感，并利用Gyrator-capacitor法对该集成电感的绕线方式建立了PSpice仿真模型。通过仿真，验证了这种集成电感能很好地克服耦合电感存在的缺点，其工作特性接近于两个分立电感。     

Chip-level integration of RF MEMS on-chip inductors using UV-LIGA technique

This paper presents a chip-level integration of radio-frequency (RF) microelectromechanical systems (MEMS) air-suspended circular spiral on-chip inductors onto MOSIS RF circuit chips of LNA and VCO using a multi-layer UV-LIGA technique including SU-8 UV lithography and copper electroplating. A high frequency simulation package, HFSS, was used to determine the layout of MEMS on-chip inductors with inductance values close to the target inductance values required for the RF circuit chips within the range of 10%. All MEMS on-chip inductors were successfully fabricated using a contrast enhancement method for 50 μm air suspension without any physical deformations. High frequency measurement and modeling of the integrated inductors revealed relatively high quality factors over 10 and self-resonant frequencies more than 15 GHz for a 1.44 nH source inductor and a 3.14 nH drain inductor on low resistivity silicon substrates (0.014 Ω cm). The post-IC integration of RF MEMS on-chip inductors onto RF circuit chips at a chip scale using a multi-layer UV-LIGA technique along with high frequency measurement and modeling demonstrated in this work will open up new avenues with the wider integration feasibility of MEMS on-chip inductors in RF applications for cost-effective prototype applications in small laboratories and businesses.     

Fabrication of planar and three-dimensional microcoils on flexible substrates

Inductors are basic components of magnetic sensors. Generally, with those sensors, a weak magnetic variation has to be detected. As the sensitivity increases with the inductance value, our objectives are to design inductors with a maximum of turns while keeping millimetric sizes for the sensor. In this work, we present two microcoil fabrication processes compatible with rigid and flexible substrates. The first one is used for the realization of planar microcoils with one step of copper micromoulding. For example, a 40-turn microcoil of 1 mm external diameter and 5 μm copper width and spacing wires has been obtained. The second process allows the fabrication of three-dimensional microcoils (microsolenoids). It is based on two steps of copper micromoulding. In this process, a grey-tone photolithography step is implemented. Microsolenoids with 10–13 wires have been realized.

     

Geometrical analysis of planar coil design for fluxgate magnetometer

This paper presents geometrical analysis on the design of planar coupled coils for use as magnetic sensors. Inductance and magnetic coupling of the coil are analyzed using field solver analyzer ASITIC. Effects of different coil parameters, such as winding number, spacing, and width are discussed in detail. As results, the coil design considers not only the inductance value and the height of magnetic coupling, but also the geometrical area consumed. The analysis is verified by experimental data from coupled coil fabricated using surface micromachining techniques. An outer coil area having a typical dimension of 1.8 × 1.8 mm² and a fix inner coil diameter of 500 μm was fabricated. Coupling factor of about 0.7 and self inductance of 12.7 nH were achieved, which show a reasonably good agreement with the simulated results. The coil platform developed offers an integrated solution for the design of fluxgate magnetometer.     

片上射频磁介质电感的设计与仿真

片上无源电感是RF IC中需求很高的器件.将适宜的磁材料引入到射频微电感中,既可有效地提升电感L值,从而使电感所需面积减小,又能保持甚或提升电感Q值,是实现高性能、小尺寸射频微电感的一种非常有前景的方法.我们设计了不同结构的磁介质微电感,通过软件仿真研究了电感结构和材料参数变化对电感性能的影响,为研制小尺寸、高性能片上磁介质电感提供了理论指导.     

“Ni–Zn铁氧体颗粒–光刻胶”覆盖的 片上射频电感

本文报道了采用新型"纳米颗粒一光刻胶"混合旋涂技术制作的片上射频Ni-Zn铁氧体磁膜微电感.成相良好的Ni0.3Zn0.6Cu0.1Fe2O4铁氧体纳米颗粒在光刻胶中均匀混合,再将该混合物涂覆在螺旋电感线圈上,实现电感性能的提升.这种新型低温工艺避免了常规制作铁氧体器件方法带来的高温处理(>600℃)对集成电路的破坏.与无磁膜覆盖样品对比,铁氧体覆盖电感的电感量在0.1～4 GHz提升了14～27%.这是实现高性能、全兼容铁氧体集成片上RF IC电感的一种很有前景的途径.     

Fabrication of planar and three-dimensional microcoils on flexible substrates

Inductors are basic components of magnetic sensors. Generally, with those sensors, a weak magnetic variation has to be detected. As the sensitivity increases with the inductance value, our objectives are to design inductors with a maximum of turns while keeping millimetric sizes for the sensor. In this work, we present two microcoil fabrication processes compatible with rigid and flexible substrates. The first one is used for the realization of planar microcoils with one step of copper micromoulding. For example, a 40-turn microcoil of 1 mm external diameter and 5 μm copper width and spacing wires has been obtained. The second process allows the fabrication of three-dimensional microcoils (microsolenoids). It is based on two steps of copper micromoulding. In this process, a grey-tone photolithography step is implemented. Microsolenoids with 10–13 wires have been realized.     

Surface micromachined high-performance RF MEMS inductors

High-performance three-dimensional (3-D) microinductors with air-core and polyimide-core were fabricated by using simple MEMS technology. Both inductors have electroplated copper coils to minimize resistance to obtain high quality factor. The measurement results show that both inductors have high Q-factors over wide range of operating frequency. The maximum Q-factor of the polyimide-core is 36.5 and the inductance is 1.42 nH at 4.5 GHz, while the maximum Q-factor of the air-core inductor is 22.9 and the inductance is 1.17 nH at 5.5 GHz. The series resistance/parasitic capacitance of the polyimide-core inductor and air-core inductor is 1.05 Ω/1.07 pF and 1.82 Ω/0.57 pF respectively at the peak-Q frequency.     

Achieving high sensing in 0.5 nA for the driving pixel currents in AMOLEDs with settling time of 7 µs by a new external current sensing circuit

A new external current sensing circuit with baseline compensation for the active matrix organic light emitting diode (AMOLED) display is developed herein to achieve the sensing precision of 0.5 nA in pixel with 7 µs of settling time. Current sensing circuit incorporates a new push–pull transient current feedforward whereas the current analog to digital converter (CADC) based digital baseline current compensation incorporates an 11-bit current digital-to-analog converter, a current comparator and a digital control circuit with an 11-bit successive approximation register. The proposed integrated mixed signal IC drives a 6T1C pixel-based AMOLED panel with one horizontal time of 7.7 µs at a scan frequency of 60 Hz. The design readout chip can simultaneously sense and compensate TFT baseline current variation. The readout circuit and the baseline compensation circuit are implemented in the integrated chip with chip area of 125 μm × 46 μm and fabricated via TSMC T18 process. With the standard 3.3 V supply, experimental result shows that the overall power consumption of the chip is 988 µW watt. The minimum LSB current for the CADC is 10 nA and the maximum achievable sampling rate is 500 KS/s. The measured INL and DNL of CADC is 0.84 and 0.98 respectively. Despite of heavy data line parasitic capacitances (2.6 KΩ/20 pF) of the AMOLED display, experimental results show that the proposed circuit can sense 0.5 nA current within 7 µs of settling time. The sensing precision of 0.5 nA within 7 µs are the best among all reported literature to date whereas the current sense range (0.5–500 nA), system sampling rate (142 KS/s), INL (0.84) and DNL (0.98) of the CADC is approximately comparable among all reported.

     

Electrostatically driven tunable radio frequency inductor

An electrostatically driven tunable radio frequency (RF) inductor with large inductance tuning range consisting of electroplated soft magnetic permalloy (Ni₈₀Fe₂₀ alloy) plate was proposed in this paper. The fabricated tunable inductor exhibits a large tunable inductance range up to 77.8%, together with improved quality factor (Q-factor) at high frequencies. Such tunability of inductance and Q-factor was due to the magnetoelectric coupling effect between the soft magnetic permalloy plate and the spiral inductor, which lead to the magnetic flux of the inductor and mutual inductance change. The concept of tuning inductance by using electroplated soft magnetic permalloy has large potential for wide range RFIC applications.     

RF MEMS continuous reversible variable inductor based on a microfluidic network

In this work, RF MEMS continuous reversible variable inductor has been fabricated by using microelectronic technology and lamination process. We review, evaluate and compare this variable inductor with other work. The proposed inductor is a dual circular coil and has an inductance of few nH. The fundamental idea is to place a liquid droplet between the metal turns of a coil in order to modify the capacitive/resistive coupling between metal tracks and hence to change the stored magnetic energy. The SU-8 resin was used to realize the microfluidic channels and Au as metallic tracks. To prove the reversibility of the inductor, two cases were studied: filling and emptying of channels. The tuning range of the inductance is approximately 107 % at 1.6 GHz, making these devices very suitable as building blocks in many RF applications.     

Design of new microchannel to reduce applied voltage for microparticles separation using dielectrophoresis method

This paper presents a new structure of microchannel in order to reduce the applied voltage using dielectrophoresis (DEP). DEP is one of the most popular techniques to separate microparticles which needs an electric field in microfluidic devices. In this study, the AC-DEP sidewall electrodes are used. The novelty of this research is to change the outlet microchannel size which effectively reduces applied voltage. In previous work, in order to separate particles with 3.5 and 4 µm diameters, 4.5 V was needed. In new design, we keep all effective parameters constant and change one of the outlet microchannel size from 50 to 60, 70 and 80 µm. Therefore, in order to separate the microparticles, we need only 3, 2 and 1.3 V, respectively.

     

A novel microfluidic high-throughput resistive pulse sensing device for cells analysis

Microfluidic impedance-based devices offer a simple method for counting and sizing particles and cells in fields of biomedical research and clinical diagnosis. In this work, we present design, fabrication and operational characteristics of a novel high throughput original MEMS-based Coulter counter. This microfluidic device possesses two sub channels including two pairs of coplanar Au/Cr electrodes in each channels which allows double detection of the particles simultaneously and increases the throughput. The present design provides minimizing the cross talk and obviating the need for hydrodynamic focusing of the sample particles by adjusting Y shape insulation obstacle in direction of flow. Moreover, reducing coincidence events and removing electrode polarization effect were purposed by applying optimum sizes for electrodes considering the ease of fabrication and low costs. The reliability of the novel device was evaluated for polystyrene particles and cancer cells in conductive solutions. Results, which were recorded as relative resistance pulses across four sensing zones, illustrate the capability of the double-channel proposed device in detecting, counting and sizing 10 and 20 µm polystyrene particles. The superiority of present design was proved by relative counting error of below 3 and 11% for the 10 µm and 20 µm particles, respectively and a throughput of hundreds particles per second. Aiming at demonstrating the functionality of the proposed device in the biomedical area, counting of SP2/0 cells was performed. The measured counting outputs for cells in the size range of 5.63–17.6 µm were validated with results of hemocytometer cell counter, with relative error less than 7%.

     

Sandwich structure based on back-side etching silicon (100) wafers for flexible electronic technology

An SU-8-silicon(100)-SU-8 flexible composite sandwich structure is studied. Besides preventing corrosion to the thin silicon membrane, SU-8 photoresist coated on the silicon membrane improves its flexibility as shown by an ANSYS finite element simulation. Using a plasma enhanced chemical vapor deposited SiO₂/Si₃N₄ composite film as an etch mask on the polished side, a 4″ (100) silicon wafer was thinned to 26 µm without rupture in a 30 wt% KOH solution. The wafer was coated on both sides with 20 µm of SU-8 photoresist and then bent over cylinders with various diameters, to flex the sandwich in a controlled manner. The determined minimal bending radius of the fabricated thin silicon-based sandwich structure is approximately 3.5 mm. The fabrication of this sandwich structure is compatible with conventional microelectronic fabrication processing. Thus, it allows one to thin fully fabricated devices in a post-fabrication process to make high-performance flexible electronics.

     

Polymer-core conductor approaches for RF MEMS

In many radio frequency (RF) microelectromechanical systems (MEMS) applications, currents are confined to the outermost portions of conductors due to the skin effect. Conductors consisting of polymer cores coated with metal, the so-called polymer-core conductor, are appropriate to consider for these applications, and in many instances are easier to fabricate than their solid-metal-core counterparts. Implementation of polymer-core conductors using an SU-8 epoxy-core patterning and subsequent metal electrodeposition is reported. The SU-8 core approach allows for relatively simple formation of extremely high-aspect-ratio columns for inductor sidewalls. In addition, an SU-8 bridge fabrication technique has been realized using a double exposure and single develop scheme. The bridge thickness has been characterized as a function of the optical dose and the post bake time in an oven. Three-dimensional, high-aspect-ratio, high Q-factor, solenoid-type RF inductors are fabricated and tested to demonstrate the feasibility of the polymer-core conductor approach for RF applications. A single, vialess metallization over SU-8 back-bone structure provides the complete conducting paths of the inductor. A single turn inductor that is 900 /spl mu/m in height and 600 /spl mu/m in lateral extension shows a maximum Q-factor of 84 and an inductance of 1.17 nH at 2.6 GHz.     

High performance suspended spiral inductor and band-pass filter by wafer level packaging technology

Suspended inductors and 2.45 GHz BPF with patterned ground shields on the lossy silicon substrate by using Cu/BCB based wafer level packaging and bulk Si etching technologies were fabricated. Thick BCB interlayer is used as the supporting dielectric and the backside cavity is easily removed by using a two-step back-etching process. The fabricated 2.7 nH inductor has a maximum Q factor 49 at 8.2 GHz and high Q factors more than 22 in the broadband frequency range from 1 to 10 GHz. And the realized 2.45 GHz BPF has the insertion loss of 3.0 dB and the return loss of more than 14 dB at the pass band. It is also featured by more than 48 and 25 dB attenuation at 0.9 and 1.8 GHz respectively, with the second harmonic rejection being 33 dB.

     

Modeling, optimization and performance of high-Q MEMS solenoid inductors

Modeling, optimization and performance of on-chip solenoid inductors is presented. MATLAB is used to get the π-equivalent circuit model parameters. The effects of the geometrical parameters on the inductance and quality factor (Q-factor) are different. Normally, the performance of the inductors can be improved by increasing the coil turns in a way and increasing the length of the conductor, but both of them will occupy more chip area, which is not good for the minimization of the on-chip system. It is desirable to improve the performance of inductor by increasing the height of the via. Of the three types of fabricated inductors covering the same area, the inductors with the height of via 15, 30 and 45 μm have high performance. The self-resonant frequency is up to 10 GHz. The inductances and Q-factors at peak-Q frequency (about 5.8 GHz) are 1.16, 1.35, 1.78 nH and 21.9, 27, 38, respectively.     

High-performance inductors using capillary based fluidic self-assembly

In this paper, a batch microfabrication process is presented for creating high aspect ratio, micron-sized helical and toroidal inductors with Q greater than or equal to 50 at multi-GHz frequencies. With a maximum processing temperature of only 220/spl deg/C, the inductors can be fabricated on top of standard CMOS wafers. This process can also be used to create "inductor chiplets", which are polymer-encapsulated inductors with the same form factor as an EIA (Electronics Industries Association) standard 0201 surface mount device. The chiplets can be assembled onto CMOS wafers using a fluidic microassembly technique. This technique allows for multiple electrical interconnects to the inductor chiplets. The 40-/spl mu/m gap between the substrate and assembled inductor increases the Q by a factor of /spl sim/3 compared to as-fabricated inductors. Assembled and as-fabricated inductors have been characterized on similar substrates and have maximum Q values of 50 and 15 with resonant frequencies of 10 GHz and 9 GHz, respectively. Performance of the assembled inductors is nearly comparable to that of inductors as fabricated and tested on quartz substrates.     

High aspect ratio air core solenoid inductors using an improved UV-LIGA process with contrast enhancement material

In this paper, we investigate the application of a contrast enhancement material (CEM388SS^®, Shin-Etsu MicroSi, Inc., AZ, USA) on thick SU-8 negative photoresist (Microchem Corp., MA, USA) and its use in the construction of a high aspect ratio on-chip solenoid inductor. Various SU8 test microstructures (with aspect ratio of 10:1 and 20:1) were first constructed by utilizing this improved UV-LIGA process to demonstrate the clear difference before and after the application of CEM. It was found that this material dramatically reduced the “T-topping” effect and improved the structural profile angle; and higher aspect ratio microstructures could be achieved without modification/upgrades of any kind on the existing lithography tool. Furthermore, we implemented this process in the fabrication work of high aspect ratio air core solenoid inductor and obtained a very high quality (Q) factor of 72.8 at 9.7 GHz from a 3-turn inductors and a high inductance of 28 nH from a 20-turn inductor. Experimental data showed that inductors with taller via structures (higher aspect ratio) had better radio frequency (RF) characteristics than those of lower via structures, which are highly desirable in many communication applications.