An wide-range tunable on-chip radio-frequency LC-tank formed with a post-CMOS-compatible MEMS fabrication technique

An on-chip-micromachined tunable LC-tank, which consists of a metal inter-digitated variable capacitor and a metal solenoid inductor, is developed for wide-range radio-frequency (RF) tuning in multi-GHz band. A low-temperature metal MEMS process is developed to on-chip fabricate the passives. The process can be used for post-CMOS-compatible integration with RF ICs. Both the varactor and the inductor are suspended with a gap from the low-resistivity silicon wafer (i.e. standard CMOS wafer) for effectively depressing RF loss. The fabricated variable capacitor part, the inductor part and the whole tunable LC resonator are sequentially tested, finally resulting in a wide resonance-frequency tuning range of 72% (between about 3.5 and 6.0 GHz) under a low tuning voltage range of 0-4 V, while the Q-factor ranged within 23 and 8.     

Design and modeling of a micromachined high-Q tunable capacitor with large tuning range and a vertical planar spiral inductor

In wireless communication systems, passive elements including tunable capacitors and inductors often need high quality factor (Q-factor). In this paper, we present the design and modeling of a novel high Q-factor tunable capacitor with large tuning range and a high Q-factor vertical planar spiral inductor implemented in microelectromechanical system (MEMS) technology. Different from conventional two-parallel-plate tunable capacitors, the novel tunable capacitor consists of one suspended top plate and two fixed bottom plates. One of the two fixed plates and the top plate form a variable capacitor, while the other fixed plate and the top plate are used to provide electrostatic actuation for capacitance tuning. For the fabricated prototype tunable capacitors, a maximum controllable tuning range of 69.8% has been achieved, exceeding the theoretical tuning range limit (50%) of conventional two-parallel-plate tunable capacitors. This tunable capacitor also exhibits a very low return loss of less than 0.6 dB in the frequency range from 45 MHz to 10 GHz. The high Q-factor planar coil inductor is first fabricated on a silicon substrate and then assembled to the vertical position by using a novel three-dimensional microstructure assembly technique called plastic deformation magnetic assembly (PDMA). Inductors of different dimensions are fabricated and tested. The S-parameters of the inductors before and after PDMA are measured and compared, demonstrating superior performance due to reduced substrate loss and parasitics. The new vertical planar spiral inductor also has the advantage of occupying much smaller silicon areas than the conventional planar spiral inductors.     

IOGHz 0.25μm CMOS LC压控振荡器

采用标准0.25μm CMOS工艺实现了10GHz LC压控振荡器.为了适应高频工作,并实现低相位噪声,该压控振荡器采用了手动优化的带中心抽头的对称电感,将A-MOS变容二极管与无源金属-绝缘层-金属电容串联,并采用了带LC滤波器的尾电流源.测试结果显示,当振荡频率为10.2GHz时,在1MHz频偏处相位噪声为-103.2dBc/Hz,调谐范围为11.5%.供电电压为3.3V时,核心电路功耗为9.0mW.芯片面积为0.67mm×0.58mm.     

Tunable MEMS LC resonator with large tuning range

A tunable resonator based on MEMS technology is reported. The resonator is a parallel LC type resonator, in which the capacitor is made up of two metal bridges and the inductor is made up of a shorted stub. The length of the shorted stub is changed by shunt DC contact switches and therefore inductance values of the resonator can be varied. As a result, the resonant frequency of the resonator can be shifted from 8 to 14 GHz with 75% tunable range. The whole size of the resonator is 6/spl times/0.9 mm/sup 2/.     

A 1.8-2.6 GHz CMOS VCO with switched capacitor array and switched inductor array

The design of a 1.76-2.56 GHz CMOS voltage-controlled oscillator(VCO)with switched capacitor array and switched inductor array is presented.Fabricated in 0.18μm 1P6M CMOS technology,the VCO achieves a 37% frequency tuning range.The measured phase noise varies between-118.5 dBc/Hz and-122.8 dBc/Hz at 1 MHz offset across the tuning range.Power consumption is about 14.4 mW with a 1.8 V supply.Based on a reconfigurable LC tank with switched capacitor array and switched inductor array,the mnmg range is analyzed and derived in terms of design parameters,yielding useful equations to guide the circuit design.     

一种新偏压结构的BST电容梳状滤波器设计

介绍了一种五阶可调抽头式梳状线滤波器,设计采用共面方式接地,使用Ba0.6Sr0.4TiO3 (BST)铁电薄膜平板电容作为可调部件,并分析了平板电容结构的影响.针对梳状电调滤波器需单阶加压和外接大电阻繁琐的情况,提出利用集成在衬底上的大容量BST电容作为隔离电容,将各阶谐振器的偏压线互连来简化加压过程.运用高频电磁仿真软件HFSS进行验证,设计出的滤波器中心频率可调范围为842～960 MHz(14％),3 dB带宽为9％～10％.     

A 25–75-MHz RF MEMS Tunable Filter

This paper presents a state-of-the-art discrete RF microelectromechanical systems (MEMS) tunable filter designed for 25-75-MHz operation. This paper also presents an enhanced model of the RF MEMS switch, which is used for accurate prediction of the tunable filter response. The two-pole lumped-element filter is based on digital capacitor banks with on-chip metal-contact RF MEMS switches and lumped inductors, and results in a tuning range of 3:1 with fine frequency resolution, and a return loss better than 13 dB for the entire tuning range. The relative bandwidth of the filter is 4 plusmn 1% over the tuning range and the insertion loss is 3-5 dB, limited mostly by the inductor Q and the switch loss. The IIP₃ measurements prove that tunable filters with metal-contact series RF MEMS switches show extremely linear behavior (IIP₃ > 68 dBm).     

Post-CMOS micromachined RF varactor with mutual-isolated large-tuning capacitor and low-voltage actuator

A micromachined tunable capacitor is presented with the variable capacitor electrically isolated from the electrostatic actuator for flexible circuit application. Fabricated in low-resisitivity silicon wafer with CMOS-compatible processes, the device exhibits a large tuning range of 218% under 4 V driving, as well as a high Q-factor of 115 at 1 GHz and a high self-resonance frequency of 9.5 GHz.     

一种采用LC谐振电路的高频差分有源电感

提出了一种采用LC并联谐振电路的新型差分有源电感,实现了宽的工作频带、高的Q值、较大的电感值和可调谐功能.采用无源电感和MOS晶体管可变电容构成LC谐振电路,减小了等效串联电阻和等效并联电容,在增大电感值、Q值的同时,扩大了工作频带.仿真结果表明,在2～7.6 GHz频率范围内,该新型差分有源电感的电感值大于26 nH...     

采用新型可调谐有源电感的频率可调谐高Q低噪声的带通滤波器

对采用双回转结构交叉耦合差分有源电感(DGC-DAI)的可调谐、高品质因子Q和低噪声差分有源带通滤波器(THQLNA-BPF)进行了研究。输入级,采用差分共基-共射结构,以抑制噪声和获得高频特性;输出级,采用差分共集放大器,以获得高的驱动能力和高的隔离度;有源电感滤波网络,利用DAI电感值可宽范围调谐、高Q值和低的噪声,来分别实现BPF的中心频率的宽范围调节、高Q值和良好的噪声特性;进一步地,利用变容二极管网络改善BPF中心频率的可调性和提高Q值,利用有源可调负阻网络提高BPF的Q值和进行Q值独立调节。基于WIN 0.2μm GaAs HBT工艺,利用ADS对THQLNA-BPF进行性能验证。结果表明:中心频率可在1.68 GHz~4.32 GHz范围内调谐,调谐量达2.64 GHz;最大和最小Q分别达到83.6和33.6;噪声范围为6.04 dB~8.83 dB;在中心频率为3.69 GHz时,输入1 dB压缩点为-7.3 dBm,稳定系数μ>1;静态功耗小于18 mW。     

A Novel Electrically Tunable RF Inductor With Ultra-Low Power Consumption

In this study, we propose for the first time an electrically and continuously tunable RF inductor using grounded metal oxide semiconductor (MOS) transistor as a control device. By adjusting the output resistance of the grounded MOSFET, the ground-return current can lead to a significant variation in series inductance. This proposed inductor structure was implemented in a standard CMOS process and characterized up to 30 GHz, which demonstrates maximum inductance variations of 32% and 58% at 5.8 and 18 GHz, respectively. The dc power consumption of the proposed design is kept within 50 muW over the entire tuning range.     

Rotational Driven RF Variable Capacitors With Post-CMOS Processes

A ring-shaped on-chip tunable capacitor is proposed and fabricated with CMOS-compatible micromachining processes for radio frequency integrated circuits (RFICs). The rotationally driven variable capacitor features a much higher axial mechanical stiffness compared to its conventional straight-line-driven counterpart, and therefore, can effectively depress the instability caused by environmental vibration when the varactor is used in mobile systems. Meanwhile, the rotationally driven intedigitated capacitor is designed to be very flexible for wide range of electrostatic tuning. Near-room-temperature micromachining techniques are developed for post-CMOS integrating the tunable capacitors into RFIC chips. The fabricated varactor is measured with a tuning ratio of 2.1:1 under an actuation of 12 V. Q-factor is measured as 51.3 at 1 GHz and 35.2 at 2 GHz, while self-resonance frequency is as high as 9.5 GHz. The rotationally driven tunable capacitor shows about two orders of magnitude higher antivibration capability compared to the conventional straight-driven one. Therefore, the high-performance CMOS-compatible tunable capacitors are promising for practical RFIC applications in mobile electronic telecom systems.     

An Active Recursive RF Filter in 0.35 μm BiCMOS

An active recursive filter approach is proposed for the implementaion of an inductorless, tuneable RF filter in BiCMOS. A test circuit was designed and manufactured in a 0.35 μm SiGe BiCMOS technology. In simulations, the feasibility of this type of filter was demonstrated and reasonably good performance was obtained. The simulations show a center frequency tuning range from 6 to 9.4 GHz and a noise figure of 8.8 to 10.4 dB depending on center frequency. Gain and Q-value are tunable in a wide range. Simulated IIP-3 and 1-dB compression point is ?26 and ?34 dBm respectively, simulated at the center frequency 8.5 GHz and with 15 dB gain. Measurements on the fabricated device shows a center frequency tuning range from 6.6 to 10 GHz, i.e. slightly higher center frequencies were measured than the simulated.     

自跟踪陷波器

本文提出一种自动调谐陷波器,其陷波中心频率自动跟踪市电频率或某一外加干扰频率,以抑制其干扰.陷波器的谐振电路由LC组成,而电感L是用普遍阻抗转换器(GIC)来实现,GIC的端接电阻为压控MOS管电阻,因此可以用一电压控制此电阻以改变电感值,进而控制陷波频率.这种陷波电路可用于抑制市电频率的干扰噪声并防止测量或数据采集系统中前置放大器的饱和.实验结果表明在频率从4555Hz,其陷波频率跟踪精度优于0.5Hz,而陷波深度(串模抑制比)为3040dB.     

Flexibly tunable microwave photonic FIR filter incorporating wavelength spacing programmable, arrayed micro-mirror based optical filter

A novel tunable microwave photonic FIR filter incorporating a wavelength spacing tunable multiwavelength filter based on a programmable arrayed micro-mirror device (AMMD) is demonstrated. Owing to the unique characteristic of the AMMD, that an arbitrary optical filter shape can be produced by defining a desired spatial pattern on an array of /spl sim/800 000 micro-mirrors, a wavelength spacing tunable multiwavelength optical filtering pattern is readily obtainable. By controlling the optical filter wavelength spacing, flexible resonance RF frequency tuning is achieved over a range of 2.3 GHz.     

5GHz0.18μm CMOS宽带LC VCO

采用0.18μm RF CMOS工艺,设计了一个5GHz的宽带电感电容压控振荡器。该压控振荡器的电路结构选用互补交叉耦合型,采用噪声滤波技术降低相位噪声,并采用开关电容阵列扩展其调谐范围。后仿真结果表明,实现了4.44～5.44GHz的宽调谐。振荡器的电源电压为1.8V,工作电流为2.78mA,版图面积为0.37mm2。     

一个自调谐,自适应的1.9GHz分数/整数频率综合器

本文提出了一个具有自调谐,自适应功能的1.9GHz的分数/整数锁相环频率综合器.该频率综合器采用模拟调谐和数字调谐相结合的技术来提高相位噪声性能.自适应环路被用来实现带宽自动调整,可以缩短环路的建立时间.通过打开或者关断 ΣΔ 调制器的输出来实现分数和整数分频两种工作模式,仅用一个可编程计数器实现吞脉冲分频器的功能.采用偏置滤波技术以及差分电感,在片压控振荡器具有很低的相位噪声;通过采用开关电容阵列,该压控振荡器可以工作在1.7GHz~2.1GHz的调谐范围.该频率综合器采用0.18 μ m,1.8V SMIC CMOS工艺实现.SpectreVerilog仿真表明:该频率综合器的环路带宽约为100kHz,在600kHz处的相位噪声优于-123dBc/Hz,具有小于15 μ s的锁定时间.     

基于色散光纤环级联结构的可调谐带通微波光子滤波器

提出并验证了一种宽调谐带宽的带通微波光子滤波器设计方案。该滤波器借助可调谐光纤光栅Sagnac环对宽带光源进行均匀切割,产生波长间隔可调的连续光载波作为滤波器的抽头,结合色散光纤环级联结构,实现滤波器的可重构性。研究结果表明,在光电调制器和光电探测器的频率带宽足够大的情况下,当光纤光栅Sagnac环的臂长差在0.50~8.28mm内变化、可调谐光纤延迟线的最小变化步长为0.01mm时,该方案能够实现滤波器中心频率在8.0506~1333.2000GHz内调谐,调谐步长为161.01MHz,边瓣抑制比达到27dB。     

A Wide Tuning-Range CMOS VCO With a Differential Tunable Active Inductor

By utilizing a differential tunable active inductor for the LC-tank, a wide tuning-range CMOS voltage-controlled oscillator (VCO) is presented. In the proposed circuit topology, the coarse frequency tuning is achieved by the tunable active inductor, while the fine tuning is controlled by the varactor. Using a 0.18-$muhbox m$CMOS process, a prototype VCO is implemented for demonstration. The fabricated circuit provides an output frequency from 500 MHz to 3.0 GHz, resulting in a tuning range of 143% at radio frequencies. The measured phase noise is from$-$101 to$-$118 dBc/Hz at a 1-MHz offset within the entire frequency range. Due to the absence of the spiral inductors, the fully integrated VCO occupies an active area of$hbox 150times hbox 300 muhbox m^2$.     

A Tunable RF MEMS Inductor on Silicon Incorporating an Amorphous Silicon Bimorph in a Low-Temperature Process

A novel tunable radio frequency microelectromechanical system inductor based on the bimorph effect of an amorphous silicon (a-Si) and aluminum structural layer is presented. The outer turns of the inductor have a vertical height of 450 mum when no voltage is applied. A 32% tuning range with high inductance (5.6-8.2 nH) is achieved by the application of a voltage, with the structure completely flattening at 2 V. With no actuation, the peak quality factor is 15, and the self-resonance frequency is 7 GHz. The fact that the device is fabricated on Si in a low-temperature (150 degC) process enhances the potential for system integration