用于UHF RFID阅读器的自动频率校准模拟基带

基于0.18μm标准CMOS工艺,提出了一种适用于超高频射频识别阅读器的自动频率校准模拟接收基带。该模拟基带包含直流偏移消除电路和信道选择滤波器,直流偏移消除电路有6dB的预增益,信道选择滤波器采用8阶巴特沃斯结构。在频率校准电路的作用下,滤波器能够分别对250kHz和1.35MHz截止频率进行校准,校准时间小于3μs。后仿真结果表明,在3.3V电源电压下,整个模拟基带消耗12mA电流,截止频率为1.35MHz,10dB增益条件下带内输入3阶交调达到12dBm,在30dB增益时,带内噪声系数为26dB。     

UHF RFID阅读器中可编程全差分低通滤波器的设计

基于TSMC 0.25 μm RF CMOS工艺,提出了一种应用于860～960 MHz UHF波段单片射频识别(RFID)阅读器的可编程全差分低通滤波器电路.该滤波器为6阶切比雪夫有源RC滤波器,其中的运放采用带共模反馈的全平衡差动放大器结构(FBDDA)实现了全差分的缓冲器.仿真结果表明:该电路可以通过3位信号控制位产生截止频率为400 kHz、600 kHz、800 kHz、1 MHz以及1.3 MHz的全差分低通滤波器,1 MHz处的点噪声为20 nV/Hz,1 dB输入压缩点为15 dBm,3.3 V电源电压下电路消耗总电流为4.86 mA.     

应用于直接变频结构中的高线性度低功耗CMMB调谐器的基带电路

本文用0.35微米锗硅BiCMOS工艺设计了用于中国多媒体移动电视的模拟基带电路,此接收机芯片采用直接下变频结构。此基带电路使用了带有精确调谐系统的高线形度8阶切比雪夫低通滤波器,测试结果表明此滤波器有0.5dB的带内纹波,带宽调谐系统的误差在4%以内。在截止频率为4MHz的情况下对6MHz的信号有35dB的衰减。基带部分使用抽电流型的可变增益放大器,提供至少40dB的增益,并且带有出色的温度补偿。此基带电路的带外三阶交调量（OIP3）为25.5dBm,电源电压2.8V,总电流为16.4mA,芯片面积为1.1mm2。     

一种Doppler/FMCW双模式雷达模拟基带设计

基于55 nm CMOS工艺,设计了一种应用于24 GHz Doppler/ FMCW双模式雷达系统的模拟基带电路(ABB)。低通滤波器由两个改进型Tow-Thomas二阶节级联而成,实现了增益和带宽独立调节。采用一种基于7 bit可编程电流型数模转换器(IDAC)的两步逐次逼近型直流失调消除电路(SAR DCOC),可在Doppler模式10~600 Hz极低中频条件下,对混频器输出和基带自身直流失调进行消除。在IDAC和两级运放中混合使用BJT管,减小闪烁噪声,获得良好的低频噪声性能。后仿真结果表明,在2.5 V电源电压、模拟基带消耗电流4.9 mA下,两种模式增益范围均为6~62 dB,最大线性输入幅度(IP 1 dB)为10 dBm;62 dB增益时,Doppler模式、FMCW模式下的噪声系数分别小于42 dB、27 dB。蒙特卡罗仿真结果表明,当输入存在400 mV、200 mV直流失调时,基带输出直流失调仅为21.3 mV和16.4 mV。     

一种带有直流失调和载波泄漏矫正系统的直接变频WLAN收发机基带电路

本文介绍了一种基于IEEE 802.11a/b/g标准的双频段直接变频WLAN收发机基带电路,并引入了一些用于消除接收机直流失调和发射机载波泄漏的关键技术,从而使得该直接变频结构满足WLAN的性能指标。在接收机基带中,可变增益放大器提供62dB的增益范围且步长为2dB;直流失调矫正电路用来消除由版图不匹配和自混频造成的误差。该矫正环路有着不随增益调节而变化的高通极点和较快的稳定时间,后者通过在接收前导序列时设定1MHz的高通极点而在正常接收数据时设定30KHz的极点得以实现。发射机基带采用基于片上AD和DA的自动矫正系统来抑制载波泄漏,AD在矫正完成之后会自动关闭从而可以节省功耗。此电路采用0.35微米锗硅工艺并工作在2.85V电源电压下,接收基带放大器和直流失调消除电路共消耗17.52mA,而发射载波泄漏矫正环路共消耗8.3mA（矫正完成后为5.88mA）;其相应的芯片面积分别为0.68mm2和0.18mm2。     

用于77GHz毫米波雷达的模拟基带电路设计

实现了一个带宽和增益可配置、高线性度、低噪声的模拟基带电路,可应用于77 GHzCMOS毫米波雷达接收机.电路包括一个带宽可配置的5阶巴特沃斯低通滤波器模块、三个可编程增益放大器模块以及三个直流失调消除环路.增益范围为18～70 dB,增益步进为6 dB;带宽为200 kHz～2 MHz;噪声系数最小为24 dB;输出1-dB压缩点为5.1 dBm,在最高增益时,IIP3为-52dBm;功耗为14.6 mA@1 V.电路采用65 nm CMOS工艺实现,芯片面积为1.2×0.93 (mm2).     

应用于直接变频架构直播卫星调谐器中的具有宽调谐范围的连续时间低通滤波器

本文用0.35微米锗硅BiCMOS工艺设计了七阶巴特沃兹跨导电容低通滤波器及其片上自动调谐电路,该低通滤波器适用于采用直接变频架构的直播卫星调谐器。该滤波器的-3dB带宽截止频率具有从4MHz到40MHz的宽调谐范围。成功实现了一种新颖的片上自动调谐方案,用来调谐和锁定滤波器的-3dB带宽截止频率。测试结果表明,该滤波器具有-0.5dB的通带电压增益,+/- 5%的带宽精度,30nV/Hz1/2的等效输入噪声,-3dBVrms 通带电压三阶交调点,27dBVrms 阻带电压三阶交调点。I/Q正交两路滤波器及其调谐电路采用5V电源,在滤波器的-3dB带宽截止频率为20MHz的情况下,消耗电流13毫安,占用芯片面积0.5mm2。     

低功耗、高线性度的电流模可编程增益放大器

本文设计了一种电流模式下,带电流模直流失调消除（DCOC）电路的class-AB的可编程增益放大器。电路基于电流放大器,可以实现40dB的增益动态范围,增益步长为1dB。电流模可编程增益放大器由0.18-μm CMOS工艺实现,电路具有较宽的电流增益范围、较低的直流功耗和较小的芯片面积。放大器电路芯片面积为0.099μm2,在1.8V电压下静态电流为2.52mA。测试结果表明电路增益范围为10dB到50dB,增益误差为±0.40dB,OP1dB为11.80dBm到13.71dBm,3dB带宽为22.2MHz到34.7MHz。     

RFID系统中的低通滤波器设计

介绍了一种用于RFID系统的有源RC低通滤波器.该滤波器是一个6阶巴特沃斯型滤波器,包含三个级联的Tow-Thomas二次节.采用直流失调消除电路,有效地降低了直流失调;使用自动频率校准电路来消除温度、工艺和电压波动等对滤波器截止频率的影响.仿真结果显示,该滤波器电路的截止频率可达1.3 MHz,通带增益6 dB,12 dB,18 dB,24 dB可调,调谐精度为5％,线性度ⅡP3可达到17.6 dBm.电路采用TSMC 0.18 μm CMOS工艺实现,面积为0.6mm2,工作电压为1.8V,消耗电流3 mA.     

导航通信系统中频可变增益放大器设计

实现了一个GPS/伽利略双模导航通信系统中频可变增益放大器(中频6MHz,带宽2MHz/中频16MHz,带宽10MHz).增益有4档可调,从16dB至34dB, 每6dB一档.闭环电阻反馈结构保证了高线性度需求.在最高增益模式下,通带波纹小于0.2dB, 输入噪声小于15nV/sqrt(Hz),该放大器同时含有直流失调抑制功能.采用SMIC 0.18μm工艺,1.8V电源电压, 功耗为9mW.该接收机系统已成功流片.     

Performance improvement in tensile-strained In/sub 0.5/Al/sub 0.5/As/In/sub x/Ga/sub 1-x/As/In/sub 0.5/Al/sub 0.5/As metamorphic HEMT

This paper proposes a In/sub 0.5/Al/sub 0.5/As/In/sub x/Ga/sub 1-x/As/In/sub 0.5/Al/sub 0.5/As (x=0.3-0.5-0.3) metamorphic high-electron mobility transistor with tensile-strained channel. The tensile-strained channel structure exhibits significant improvements in dc and RF characteristics, including extrinsic transconductance, current driving capability, thermal stability, unity-gain cutoff frequency, maximum oscillation frequency, output power, power gain, and power added efficiency.     

Morphological and electrical characterization of SixCryCzBv thin films

Si_xCr_yC_zB_v thin films with several compositions have been studied for integration of high precision resistors in 0.8 μm BICMOS technology. These resistors, integrated in the back-end of line, have the advantage to provide high level of integration and attractive electrical behavior in temperature, for analog devices. The film morphology and the structure have been investigated through transmission electron microscopy analysis and have been then related to the electrical properties on the base of the percolation theory. According to this theory, and in agreement with experimental results, negative thermal coefficient of resistance (TCR) has been obtained for samples with low Cr content, corresponding to a crystalline volume fraction below the percolation threshold.Samples with higher Cr content exhibit, instead, a variation of the TCR as a function of film thickness: negative TCR values are obtained for thickness lower than 5 nm, corresponding to a crystalline volume fraction below the percolation threshold; positive TCR are obtained for larger thickness, indicating the establishment of a continuous conductive path between the Cr rich grains. This property seems to be determinant in order to assure the possibility to obtain thin film resistors almost independent on the temperature.     

Comparison between Pt/TiO2/Pt and Pt/TaOX/TaOY/Pt based bipolar resistive switching devices

Nonvolatile memories have emerged in recent years and have become a leading candidate towards replacing dynamic and static random-access memory devices. In this article, the performances of TiO₂ and TaO₂ nonvolatile memristive devices were compared and the factors that make TaO₂ memristive devices better than TiO₂ memristive devices were studied. TaO₂ memristive devices have shown better endurance performances (10⁸ times more switching cycles) and faster switching speed (5 times) than TiO₂ memristive devices. Electroforming of TaO₂ memristive devices requires~4.5 times less energy than TiO₂ memristive devices of a similar size. The retention period of TaO₂ memristive devices is expected to exceed 10 years with sufficient experimental evidence. In addition to comparing device performances, this article also explains the differences in physical device structure, switching mechanism, and resistance switching performances of TiO₂ and TaO₂ memristive devices. This article summarizes the reasons that give TaO₂ memristive devices the advantage over TiO₂ memristive devices, in terms of electroformation, switching speed, and endurance.     

Very low-noise Al/sub 0.3/Ga/sub 0.7/As/Ga/sub 0.65/In/sub 0.35/As/GaAs single quantum-well pseudomorphic HEMTs

AlGaAs/GaInAs/GaAs pseudomorphic HEMTs with an InAs mole fraction as high as 35% in the channel has been successfully fabricated. The device exhibits a maximum extrinsic transconductance of 700 mS/mm. At 18 GHz, a minimum noise figure of 0.55 dB with 15.0 dB associated gain was measured. At 60 GHz, a minimum noise figure as low as 1.6 dB with 7.6 dB associated gain was also obtained. This is the best noise performance yet reported for GaAs-based HEMTs.<>     

A 12 /spl times/ 12 In/sub 0.53/Ga/sub 0.47/As-In/sub 0.52/Al/sub 0.48/As avalanche photodiode array

We report a 12 /spl times/ 12 In/sub 0.53/Ga/sub 0.47/As-In/sub 0.52/Al/sub 0.48/As avalanche photodiode (APD) array. The mean breakdown voltage of the APD was 57.9 V and the standard deviation was less than 0.1 V. The mean dark current was /spl sim/2 and /spl sim/300 nA, and the standard deviation was /spl sim/0.19 and /spl sim/60 nA at unity gain (V/sub bias/ = 13.5 V) and at 90% of the breakdown voltage, respectively. External quantum efficiency was above 40% in the wavelength range from 1.0 to 1.6 /spl mu/m. It was /spl sim/57% and /spl sim/45% at 1.3 and 1.55 /spl mu/m, respectively. A bandwidth of 13 GHz was achieved at low gain.     

The C-V-f and G/ω-V-f characteristics of Al/SiO2/p-Si (MIS) structures

The frequency dependence of capacitance-voltage (C-V) and conductance-voltage (G/ω-V) characteristics of the Al/SiO₂/p-Si metal-insulator-semiconductor (MIS) structures has been investigated taking into account the effect of the series resistance (R_s) and interface states (N_ss) at room temperature. The C-V and G/ω-V measurements have been carried out in the frequency range of 1 kHz to 1 MHz. The frequency dispersion in capacitance and conductance can be interpreted only in terms of interface states and series resistance. The N_ss can follow the ac signal and yield an excess capacitance especially at low frequencies. In low frequencies, the values of measured C and G/ω decrease in depletion and accumulation regions with increasing frequencies due to a continuous density distribution of interface states. The C-V plots exhibit anomalous peaks due to the N_ss and R_s effect. It has been experimentally determined that the peak positions in the C-V plot shift towards lower voltages and the peak value of the capacitance decreases with increasing frequency. The effect of series resistance on the capacitance is found appreciable at higher frequencies due to the interface state capacitance decreasing with increasing frequency. In addition, the high-frequency capacitance (C_m) and conductance (G_m/ω) values measured under both reverse and forward bias were corrected for the effect of series resistance to obtain the real diode capacitance. Experimental results show that the locations of N_ss and R_s have a significant effect on electrical characteristics of MIS structures.     

Lanthanum diffusion in the TiN/LaOx/HfSiO/SiO2/Si stack

Band edge Complementary Metal Oxide Semiconductor (CMOS) devices are obtained by insertion of a thin LaO_x layer between the high-k (HfSiO) and metal gate (TiN). High temperature post deposition anneal induces Lanthanum diffusion across the HfSiO towards the SiO₂ interfacial layer, as shown by Time of Flight Secondary Ions Mass Spectroscopy (ToF-SIMS) and Atom Probe Tomography (APT). Fourier Transform Infrared Spectroscopy in Attenuated Total Reflexion mode (ATR-FTIR) shows the formation of La-O-Si bonds at the high-k/SiO₂ interface. Soft X-ray Photoelectron Spectroscopy (S-XPS) is performed after partial removal of the TiN gate. Results confirm La diffusion and changes in the La chemical environment.     

Al/sub 0.3/Ga/sub 0.7/As/In/sub x/Ga/sub 1-x/As (0/spl les/x/spl les/0.25) doped-channel field-effect transistors (DCFET's)

The properties of both lattice-matched and strained doped-channel field-effect transistors (DCFET's) have been investigated in AlGaAs/In/sub x/Ga/sub 1-x/As (0/spl les/x/spl les/0.25) heterostructures with various indium mole fractions. Through electrical characterization of grown layers in conjunction with the dc and microwave device characteristics, we observed that the introduction of a 150-/spl Aring/ thick strained In/sub 0.15/Ga/sub 0.85/As channel can enhance device performance, compared to the lattice-matched one. However, a degradation of device performance was observed for larger indium mole fractions, up to x=0.25, which is associated with strain relaxation in this highly strained channel. DCFET's also preserved a more reliable performance after biased-stress testings.<>     

Highly linear Al/sub 0.3/Ga/sub 0.7/N-Al/sub 0.05/Ga/sub 0.95/N-GaN composite-channel HEMTs

We report an Al/sub 0.3/Ga/sub 0.7/N-Al/sub 0.05/Ga/sub 0.95/N-GaN composite-channel HEMT with enhanced linearity. By engineering the channel region, i.e., inserting a 6-nm-thick AlGaN layer with 5% Al composition in the channel region, a composite-channel HEMT was demonstrated. Transconductance and cutoff frequencies of a 1 /spl times/100 /spl mu/m HEMT are kept near their peak values throughout the low- and high-current operating levels, a desirable feature for linear power amplifiers. The composite-channel HEMT exhibits a peak transconductance of 150 mS/mm, a peak current gain cutoff frequency (f/sub T/) of 12 GHz and a peak power gain cutoff frequency (f/sub max/) of 30 GHz. For devices grown on sapphire substrate, maximum power density of 3.38 W/mm, power-added efficiency of 45% are obtained at 2 GHz. The output third-order intercept point (OIP3) is 33.2 dBm from two-tone measurement at 2 GHz.