基于电容倍增技术的LDO补偿方法

设计了一种低静态电流、高稳定性的LDO稳压器.该电路使用电容倍增技术进行频率补偿,减小了补偿电容值,节省了芯片面积,在负载电流0.1mA和150mA时具有较好的相位裕度.电路采用XFAB 0.6μm CMOS工艺模型,最终设计的LDO电路静态功耗17μA,最大驱动电流150mA.使用10μF的负载电容,在负载电流变化率为150mA/100μs时,最大过冲为22mV(1.83%).     

一种瞬态响应增强的片上LDO系统设计

分析了传统LDO提高系统稳定性及瞬态响应的局限性,提出了一种片内集成补偿技术。该技术无需外挂电容和等效串联电阻(ESR),即可使系统在全负载范围内保持稳定,并具有良好的纹波抑制能力。仿真结果表明,系统空载时静态电流为46μA,且能提供200mA的最大负载电流,低频电源抑制比达到-65.6dB,启动时间只有16μs,在输出电容为10pF、负载电流以200mA/2μs突变时,最大下冲电压为120mV,上冲电压为160mV。     

一种快速瞬态响应无输出电容LDO的研究与设计

设计了一种基于自适应偏置放大器的具有快速瞬态响应的无输出电容LDO.自适应偏置放大器在发生负载瞬态响应时能够调节自身偏置电流以提供较大的输出电流来增加摆率;瞬态响应提升电路通过减小负载电容充放电电流而减小了输出电压的建立时间;通过并联反馈补偿来提高环路的稳定性.仿真结果表明,所设计的无输出电容LDO最大输出电流200mA,最小跌落电压200mV,静态电流仅16μA,全负载正负阶跃变化响应时间分别为2.5μs和3.5μs.     

一种高性能无片外电容型LDO设计北大核心CSCD

设计了一种高性能无片外电容型LDO线性稳压器.其中,EA采用推挽输出放大器设计,在静态时保持低功耗,瞬态响应时提供大的输出电流,提高LDO的响应速率.高环路增益使LDO电路具有很高的稳压精度;采用零点补偿技术,保证了LDO环路稳定性.LDO采用0.13μm CMOS工艺设计,仿真结果表明,在1.2V^2.0V输入电压下,LDO输出稳定的1.0V电压,输出负载电流为50μA^100mA,最大负载电容可达到100pF,低频PSR为-67.5dB@100mA^-85.5dB@50μA,负载调整率0.8μV/mA,LDO的静态电流为50μA,整体版图面积为0.016 3mm2.     

一种基于电流比较的无基准电压Cap-less LDO

提出了一种基于电流比较的无基准电压型Cap-less LDO。将输出电压转换为电流后与参考电流比较,无需独立的基准电压模块,可降低功耗。在环路中插入了一个带有源反馈补偿网络的误差放大器,可增加环路增益,从而提升精度,在减少片上补偿电容的同时维持宽负载范围内的环路稳定性。该LDO采用65 nm标准CMOS工艺仿真验证,仿真结果显示,当负载电容为100 pF时,静态电流为9.4 μA,片上补偿电容仅需0.25 pF,当输出负载在100 μA和50 mA之间处切换时,恢复时间小于1 μs,带有源反馈LDO的上冲和下冲分别为94 mV和21 mV,和不带有源反馈的LDO相比,上冲和下冲分别减少了28%和79%。     

一种超低静态电流LDO线性稳压器的设计

为了延长便携式、可穿戴医疗设备的待机时间,设计了一种具有超低静态电流的低压差(LDO)线性稳压器。采用误差放大器与基准电路相结合的结构,在降低静态电流的同时减小芯片面积;其次,利用负载检测模块,降低了空载及轻载时过温保护和过流保护等模块的静态电流。采用自适应偏置电流技术来动态调整稳压环路各支路的工作电流以及零点频率补偿方式,解决了静态功耗与瞬态响应和环路带宽间的矛盾。该LDO线性稳压器采用0.35μm CMOS工艺进行流片加工,测试结果表明,该LDO线性稳压器静态电流为700 nA,最大负载电流为150 mA,轻载与满载跳变时上过冲电压为63 mV,下过冲电压为55 mV。     

电流模式BUCK转换器宽占空比片内补偿方案

提出了一种适用于峰值电流模式BUCK转换器的片内补偿方案,针对宽占空比范围的情况,不用改变芯片内部补偿模块,只需微调芯片外部的一个电阻,便可以得到较好的相位裕度。本设计提高了系统响应速度,克服了稳定性对输出负载和陶瓷输出电容ESR的依赖,且设计简单,可操作性强,实现了芯片的高稳定性。采用0.25μm UMC工艺仿真,结果显示在不同占空比情况下,内部补偿均实现了良好的环路稳定性。     

一种瞬态增强的无外接电容LDO电路设计

设计了以增强型AB跟随器作为缓冲级的带瞬态增强电路的线性稳压器(LDO)。在保证LDO环路稳定性的同时,将增强型AB跟随器的偏置电流改为动态偏置电流,同时加入瞬态增强电路来改善系统重载到轻载来回跳变时的瞬态性能。仿真结果表明,该稳压器输入电压2.7~5 V,输出电压2.5 V,压差200 m V,电路空载时静态电流18μA,最大负载电流100 m A;在输出电容为100 pF时,负载电流以99×10~(–3)A/μs跳变,输出电压下冲和过冲分别为89 m V和110 m V,均在1.5μs内恢复稳定。     

一种基于密勒倍增的高性能LDO的设计

基于零极点跟踪技术,提出一种新的LDO频率补偿架构.利用密勒电容倍增原理和零极点跟踪技术,在很小的补偿电容面积下使LDO获得全负载范围内的环路稳定.摆率增强电路的应用使系统具有优越的负载瞬态调整性能.基于0.5 μm标准CMOS工艺,对LDO进行仿真验证.结果表明,系统空载下,静态电流为32 μA,且能提供最大200 mA的负载电流;在输出电容为2.2 μF、负载电流以200 mA/10 ns突变时,最大下冲电压仅为10 mV,没有明显的上冲.     

一种具有反压保护功能的微功耗LDO

本文提出并实现了一种具有反压保护功能的微功耗LDO.一方面采用新型自适应栅衬偏置技术,使导通管的栅/衬极在输入输出反压状态下自动跟踪输出电压,从而关断导通管沟道,零偏寄生衬漏体二极管,解决了反压状态下LDO的反灌电流和电路闩锁问题.另一方面,稳压环路中综合采用高效双极缓冲技术和零极点抵消频率补偿技术,既解决了微功耗LDO中的环路稳定困难问题,又使漏失电压最小.该款LDO采用BiCMOS工艺实现.测试结果表明,其反向耐压可达9V;负载调整率和线性调整率分别为0.025 mV/mA和0.6 mV/V;满负载电流(250mA)漏失电压仅为70 mV;空载和重载下静态电流分别只有7μA和7.7 μA.     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

Curved crystal spectrometer for the measurement of X-ray lines from laser-produced plasmas

In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal （200） （2d = 0.4027 nm） is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line（w）, the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line（x）, the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines（y）, the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line（z） in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line（q） in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution（λ/△ 2） is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.     

Electronic Structure of Semiconductor Nanocrystals

This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.     

A rigorous proof of MIMO channel capacity’s increase with antenna number

It is well known that adding more antennas at the transmitter or at the receiver may offer larger channel capacity in the multiple-input multiple-output（MIMO） communication systems. In this letter, a simple proof is presented for the fact that the channel capacity increases with an increase in the number of receiving antennas. The proof is based on the famous capacity formula of Foschini and Gans with matrix theory.