采用有源电容倍增器改善开关电容DC-DC变换器的性能

研究了开关电容DC-DC变换器输出电压与电容的关系,分析了变换器输出电压波纹产生的原因.针对变换器中大电容难集成的问题,提出了一种基于跨导放大器和第二代电流传输器的有源电容倍增器的新型拓扑结构.该电路只用较少的元件就可以实现开关电容变换器中的浮地和接地电容.以二阶开关电容DC-DC变换器为例,用PSPICE软件分别对采用了有源电容倍增器的新型结构和传统结构进行了仿真.结果显示,基于有源电容倍增器的开关电容变换器仅用100pF电容就等效了200nF电容的输出性能,而且具有更低的输出电压波纹.     

基于有源电容倍增器的新型电荷泵DC-DC变换器

电荷泵中浮置电容是影响输出特性的关键因素,针对大容量浮置电容难以集成的问题,提出利用电流传输器构成有源电容倍增器代替浮置电容的方法,可使等效的浮置电容容量提高1~3个数量级.利用PSPICE软件对反压及倍压电荷泵分别在采用有源电容倍增器和理想电容的情况下进行仿真,对比分析的结果说明采用有源电容倍增器的电荷泵电路仅需要很小的电容就能得到与外加大容量浮置电容电荷泵电路相同的输出特性(实例中100pF可等效50nF),从而基于有源电容倍增器的电荷泵将更易于全单片集成.     

适合集成开关电容DC-DC变换器的浮地电容倍增器

针对在集成电路中制作大容量电容器的困难，提出了一种利用电流传输器提高集成电容器容量的方法，称之为连续可变浮地电容倍增器。分析了电容倍增的机理，建立了相应的关系式，在此基础上对用此浮地电容构成的一阶滤波器和开关电容DC-DC变换器进行了理论分析和PSPICE仿真。结果表明，利用电流传输器的阻抗变换作用，可使小容量的电容等效变换为较大容量的浮地电容，从而便于开关电容DC-DC变换器实现全单片集成。     

一种基于OTA和CCII实现的n阶低通滤波器

提出了用信号流图法设计n阶基于OTA（跨导运算放大器）和CCII（第二代电流传输器）电流模式低通滤波器的方法。该滤波器由具有双输出端的平衡滤波器和第二代电流传输器及接地电容构成。与同类电路比较,设计更简便,结构更简单,无源元件全部接地,易于集成。     

基于MOCCCII-C的n阶通用电流模式滤波器

提出了一种基于多输出电流控制电流传输器的n阶通用电流模式滤波器,该滤波器采用单输入单输出的形式,电路结构简单,仅由n+1个有源器件,n个接地电容构成;采用高阻抗输出;可以通过对输出信号的选择实现不同的滤波功能,便于集成。面向实际电路完成了Pspice仿真。     

基于OTA的有源Gm-C复数带通滤波器的设计

设计了一种基于OTA的有源Gm-C复数带通滤波器,用以实现射频前端芯片中的中频滤波和镜像抑制功能,该滤波器采用Gyrator结构,将低通原型滤波器中的集总电感用有源电感进行替换,并依据复数变换理论,对浮地电容和接地电容进行复数变换,实现带通滤波器.滤波器中心频率为4.1 MHz,1 dB带宽2 MHz,带内增益13.27 dB,1.5倍带宽处抑制在40 dB以上,镜像抑制度40 dB.Gm-C滤波器集成度高,功耗低,适合于高频应用,是当前集成中频滤波器的热点.     

基于MOCCCⅡ-C的n阶通用电流模式滤波器

提出了一种基于多输出电流控制电流传输器的n阶通用电流模式滤波器．该滤波器采用单输入单输出的形式，电路结构简单，仅由n＋1个有源器件，n个接地电容构成；采用高阻抗输出；可以通过对输出信号的选择实现不同的滤波功能，便于集成。面向实际电路完成了Pspice仿真。     

基于新型CCCⅡ电流模式二阶带通滤波器设计

针对传统第二代电流传输器(CCⅡ)电压跟随不理想的问题,提出了新型第二代电流传输器(CCCⅡ)并通过采用新型第二代电流传输器(CCCⅡ)构成二阶电流模式带通滤波器,此滤波器只需使用2个电流传输器和2个电容即可完成设计。设计结构简单,其中心频率可由电流传输器的偏置电流控制。利用HSpice软件仿真分析并验证了理论设计的准确性和可行性。     

采用有源电感的小面积宽可调范围VCO

为了实现电感-电容压控振荡器(LC VCO)的全集成和小面积,同时使其振荡频率具有较宽的可调范围和较低的相位噪声,采用差分有源电感和Q值增强共源共栅电路结构,对LC VCO进行设计。采用差分有源电感代替螺旋电感,减小了芯片面积,并利用有源电感的可调性,增大了振荡频率的可调范围。采用Q值增强共源共栅电路结构,增加了LC VCO的输出功率和Q值,进而减小了相位噪声。基于TSMC 0.18 μm RF CMOS工艺,采用Cadence仿真工具对LC VCO进行仿真验证。结果表明,LC VCO振荡频率的可调范围高达129%,在偏离最大振荡频率1 MHz处,最低相位噪声为-121.4 dBc/Hz,直流功耗为11 mW,优值FOMT(考虑到调谐范围)为-193.6 dBc/Hz。     

基于MOCCCII-C的n阶电流模式滤波器

提出了一种基于多输出电流控制电流传输器的通用高阶电流模式滤波器的系统综合设计方法,该方法通过对n阶通用电流模式滤波器的传递函数进行数学分析,将其分解为n个无损积分器级联的形式,由此提出的电路结构简单,仅由n个有源器件,n个接地电容构成。并只要通过改变输入电流的接入方式和接入数目就可以实现不同的滤波功能,便于集成,面向实际电路完成P sp ice仿真。     

基于AD9951射频正弦波信号发生器的设计

介绍DDS的工作原理,设计完成以DDS器件AD9951为核心、频率范围为30～125MHz的射频正弦波信号发生器系统,可通过计算机RS232串口设置输出频率和幅度。对系统进行测试,结果表明该系统性能良好。并分析射频信号链路各部分对输出射频信号的影响。     

Performance analysis of a low power low noise tunable band pass filter for multiband RF front end

This paper presents a low power tunable active inductor and RF band pass filter suitable for multiband RF front end circuits. The active inductor circuit uses the PMOS cascode structure as the negative transconductor of a gyrator to reduce the noise voltage. Also, this structure provides possible negative resistance to reduce the inductor loss with wide inductive bandwidth and high resonance frequency. The RF band pass filter is realized using the proposed active inductor with suitable input and output buffer stages. The tuning of the center frequency for multiband operation is achieved through the controllable current source. The designed active inductor and RF band pass filter are simulated in 180 nm and 45 nm CMOS process using the Synopsys HSPICE simulation tool and their performances are compared. The parameters, such as resonance frequency, tuning capability, noise and power dissipation, are analyzed for these CMOS technologies and discussed. The design of a third order band pass filter using an active inductor is also presented.     

一个高电源抑制比的有源电感射频放大电路

提出了一种使用有源电感的电路实现方案,可用于宽带无线收发机射频放大电路的设计中.分析了有源电感的阻抗与各元件取值的关系,设计了中心频点调节电路和具有鲁棒性的偏置电路,保证工艺偏差和电源电压波动对有源电感的阻抗具有很弱的影响.在SMIC 0.18-μm工艺下进行了电路设计和流片验证,测试结果表明,使用有源电感的射频放大电路,可以得到期望的射频信号,其中心频点的调节范围为0.5～2 GHz, 能够抵御高达0.8 V的电源偏差.     

Wide tuning-range CMOS VCO based on a tunable active inductor

In this paper, a wide tuning-range CMOS voltage-controlled oscillator (VCO) with high output power using an active inductor circuit is presented. In this VCO design, the coarse frequency is achieved by tuning the integrated active inductor. The circuit has been simulated using a 0.18-µm CMOS fabrication process and presents output frequency range from 100 MHz to 2.5 GHz, resulting in a tuning range of 96%. The phase noise is –85 dBc/Hz at a 1 MHz frequency offset. The output power is from –3 dBm at 2.55 GHz to +14 dBm at 167 MHz. The active inductor power dissipation is 6.5 mW and the total power consumption is 16.27 mW when operating on a 1.8 V supply voltage. By comparing this active inductor architecture VCO with general VCO topology, the result shows that this topology, which employs the proposed active inductor, produces a better performance.     

A 233-MHz 80%-87% efficient four-phase DC-DC converter utilizing air-core inductors on package

We demonstrate an integrated buck dc-dc converter for multi-V/sub CC/ microprocessors. At nominal conditions, the converter produces a 0.9-V output from a 1.2-V input. The circuit was implemented in a 90-nm CMOS technology. By operating at high switching frequency of 100 to 317 MHz with four-phase topology and fast hysteretic control, we reduced inductor and capacitor sizes by three orders of magnitude compared to previously published dc-dc converters. This eliminated the need for the inductor magnetic core and enabled integration of the output decoupling capacitor on-chip. The converter achieves 80%-87% efficiency and 10% peak-to-peak output noise for a 0.3-A output current and 2.5-nF decoupling capacitance. A forward body bias of 500 mV applied to PMOS transistors in the bridge improves efficiency by 0.5%-1%.     

A novel self-oscillating HEMT-HBT cascode VCO-mixer using an activetunable inductor

Here we describe a unique Ka-band self-oscillating HEMT-HBT cascode mixer design which integrates an active tunable resonator circuit. The VCO-mixer MMIC integrates GaAs HEMT's and HBT's using selective molecular beam epitaxy (MBE) technology. The HEMT-HBT cascode active mixer operates similarly to a dual-gate mixer. The HBT of the cascode is used to construct a VCO by presenting the base with an HEMT tunable active inductor. The VCO can be tuned from 28.5 to 29.3 GHz while providing ≈0 dBm of output power. Operated as an upconverter, the MMIC achieves 6-9 dB conversion loss over a 31-39 GHz output frequency band. Using these active approaches, both VCO and mixer functions were integrated into a compact 1.44×0.76 mm² chip area. The active RF integrated circuit (IC) techniques presented here have direct implications to future high complexity millimeter-wave monolithic integrated circuits (MIMICs) for ultrahigh-speed clock recovery and digital radio applications     

一种适用于多波段无线通信的品质因数增强型的CMOS射频滤波器

提出了一种使用品质因数增强型的有源电感的射频带通滤波器,描述了在宽射频频段上可调谐的品质因数增强型的有源电感设计技术,而且解释了与有源电感噪声和稳定性相关的问题.该滤波器采用0.18μm CMOS工艺制造,它所占用芯片的有效面积仅为150μm×200μm.测试结果表明:该射频滤波器中心频率为2.44GHz时,3dB带宽为60MHz,中心频率可在2.07～2.44GHz范围内调谐,1dB压缩点为-15dBm,而静态功耗为10.8mW;在中心频率为2.07GHz时,滤波器的品质因数可达到103.     

一种基于130 nm CMOS工艺的K波段混频器

基于130 nm CMOS工艺,设计了工作于K波段的双平衡下变频混频器。在传统吉尔伯特单元基础上采用电流复用注入结构,减小了开关级的偏置电流,提升了开关性能。在开关级源端引入谐振电感,消除了开关共源节点处的寄生电容,抑制了射频信号的泄露,提高了增益,减小了噪声。仿真结果表明,输入射频信号为24 GHz,本振信号为24.5 GHz,本振输入功率为-3 dBm时,该混频器的转换增益为25.8 dB,单边带噪声系数为6.4 dB,输入3阶互调截点为-8.6 dBm。     

A mesoscopic ballistic electron mixer with efficient frequencyconversion at radio frequency

The voltage-current characteristic of a four-terminal mesoscopic cross is grossly nonlinear, exhibiting two clear regions of negative differential resistance (NDR). This behavior is potentially useful in millimeter wave detectors since these small devices have very low parasitic capacitance and great sensitivity. The device exploits a planar GaAs technology which lends itself to integrated systems. We have exploited one of the NDR regions (at a current of only 1.9 μA) to carry out frequency conversion. At low frequency we observed efficient frequency doubling, with the second harmonic exceeding the fundamental by up to 10 dB at the output. We have also operated the device at radio frequency (5 MHz) and demonstrated both asynchronous and heterodyne amplitude demodulation. The effect of DC current bias was examined and it was shown that biasing the device close to the NDR gave the optimum frequency conversion. A conversion loss in the heterodyne mixer circuit of 3 dB was achieved     

基于BOOSt结构下不连续导电模式的PFC电路

采用现代高频功率变换技术的有源功率因数校正（Power Factor Corrector,PFC)技术是解决高频开关变换器谐波污染的有效手段。与传统的PFC电路相比，有源PFC电路的输入电流接近正弦波且与输与电压同相位，能有效抑制电流波形畸变和谐波，因此避免了对同一电网设施的干扰。在PFC电路中，Boost变换器是研究和应用得最多的一种变换器。本文着重分析了Boost电路在不连续导电模式状态下，PFC电路的临界条件，对实际电路结构的设计有很好的指导意义。