A New RF CMOS Gilbert Mixer With Improved Noise Figure and Linearity

The noise figure of an RF CMOS mixer is strongly affected by flicker noise. The noise figure can be improved using pMOS switch circuits, which insert current at the on/off crossing instants of the local oscillator switch stage because the circuits reduce the flicker noise injection. When it is applied to a conventional Gilbert mixer, the injection efficiency and linearity are degraded by the nonlinear parasitic capacitances of the pMOS switch circuits and the leakage through the parasitic path. We propose the pMOS switch circuits with an inductor, which tunes out the parasitic components at 2f_o and closes out the leakage path. The mixer fabricated in 0.13-mum CMOS at 2.4-GHz center frequency has provided improved characteristics for linearity and noise figure.     

一种低电压、低噪声、高增益CMOS折叠式混频器

针对IEEE802.154协议设计了一种工作于2.44GHz的900mV低电压、低噪声、高增益CMOS折叠式混频器,并在混频器的开关级共源节点引入LC回路吸收寄生电容,进一步提高了混频器的主要性能.在chartered0.18tanCMOS工艺下采用SpectreRF进行仿真,仿真结果表明:该混频器的转换增益高达18.6dB,单边带噪声系数(SSB NF)仅为7.15dB,输入/输出三阶截断点(IIP3/OIP3)为-8.77/9.88dBm,功耗为52mW.     

RF-Over-Fiber Links With Very Low Noise Figure

Previously published analytical models for the noise figure of an amplifierless fiber-optic link fail to predict the measured performance, with a discrepancy of 1.1 dB at 1 GHz that increases to 2.3 dB by 12 GHz. We use an equivalent circuit to derive the effect of an additional source of noise not accounted for in earlier models: thermal noise arising from loss in the modulator's traveling-wave electrodes. The electrode thermal noise has a frequency dependence matching that of the link's noise figure, such that predictions using the improved model match the measured 1–12 GHz performance of a link with record low noise figure to within $sim$ 0.4 dB across this band.      

一种高线性度低噪声下变频混频器

采用SMIC 0.18 μm RF CMOS工艺,设计了一种高线性度、低噪声下变频混频器。通过分析跨导级电流3阶展开项系数,优化跨导级偏置电压,在跨导级与开关级之间增加谐振频率为射频信号频率的LC并联谐振电路,在提高电路线性度的同时优化了信噪比。后仿真结果表明,在射频频率为1.575 GHz,本振频率为1.571 GHz,中频频率为4 MHz时,本振功率为0 dBm,电压转换增益为19.22 dB,输入3阶交调点为21.93 dBm,单边带噪声系数为11.74 dB。混频器工作电压为1.8 V,功耗为3.66 mW,核心电路版图面积为0.207 5 mm²。     

一种低噪声高线性度CMOS上变频混频器

设计实现了一种采用开关跨导型结构的低噪声高线性度上变频混频器,详细分析了电路的噪声特性和线性度等性能参数,本振频率为900 MHz。芯片采用0.18μm Mixed signal CMOS工艺实现。测试结果表明,混频器的转换增益约为8 dB,单边带噪声系数约为11 dB,输入参考三阶交调点(IIP3)约为10.5 dBm。芯片工作在1.8 V电源电压下,消耗的电流为10 mA,芯片总面积为0.63 mm×0.78 mm。     

A New Low Voltage RF CMOS Mixer Design

A new architecture of CMOS low voltage downconversion mixer is presented.With 1.452GHz LO input and 1.45GHz RF input,simulation results show that the conversion gain is 15dB,IIP3 is －4.5dBm,NF is 17dB,the maximum transient power dissipation is 9.3mW，and DC power dissipation is 9.2mW.The mixer’s noise and linearity analyses are also presented.     

一种新的射频CMOS混频器结构

提出了一种低电压高增益CMOS下变频混频器的新结构.这个结构避免了堆叠晶体管,因此可以在低电压下工作.在LO信号的频率为1.452GHz,RF信号频率为1.45GHz的情况下,仿真结果表明:混频器的增益为15dB,ⅡP3为-4.5dBm,NF为17dB,最大瞬态功耗为9.3mW,直流功耗为9.2mW.并对该混频器的噪声特性和线性度进行了分析.     

Noise Figure for a Mixer Diode (Correspondence)

Equations are presented for the noise figure of a mixer using a resistive diode. These results are more general than those presented previously by Barber.     

One Aspect of Minimum Noise Figure Microwave Mixer Design

A theory is derived which enables a direct measurement of the optimum RF impedance for minimum noise figure. This is achieved by an extension of Pound's method for loss measurements. Also, an analysis is made of the relation between minimum noise figure and maximum gain of the mixer represented as a two-port network. The procedure consists of first matching the RF signal input terminals with short-circuited IF terminals. Next open-circuited IF terminal conditions are obtained by a circuit used by Pound. Then a reference plane is determined coinciding by preference with the plane of a maximum in the standing wave pattern of VSWR = r. A discontinuity is finally introduced that would have a VSWR of p = /spl radic/r and have its maximum or minimum at the plane of reference.     

一种0.9V低电压低本振功率CMOS有源混频器

设计了一种可工作于0.9 V低电压和-5 dBm本振功率的CMOS有源混频器.通过在MOS管栅极和衬底间引入耦合电容,利用衬底效应加快MOS管的导通和截止,使开关对的开关状态更理想,有效地降低混频器的噪声并提高其线性特性.采用0.18 μm CMOS工艺设计,在2.45 GHz本振信号和2.44 GHz射频信号输入下,实验结果表明该混频器可有效地实现混频且具有较好的性能指标:电压转换增益为12.4 dB,输入三阶截断点为-0.6 dBm,输入1dB压缩点为-3.4 dBm,单边带噪声系数为12 dB.     

一种低噪声、高增益的直接下变频混频器

针对零中频接收机的应用,提出了一种低噪声、高增益的直接下变频混频器,并用0.25μmCMOS工艺实现。这种混频器结构采用电流复用注入技术,并且在开关管的共源端并联了一个谐振电感。电流复用注入提高了转换增益;谐振电感消除了共源端的寄生电容,抑制了射频信号的泄漏,减小了由间接开关机理产生的闪烁噪声。仿真得到这个混频器输出1/f噪声的拐点频率小于100kHz。在2.645GHz的射频输入下,测试得到的转换增益为15.5dB,输入三阶交调点为-3.8dBm,在中频1M处的单边带噪声系数为9.2dB。     

CMOS低噪声放大器的噪声系数优化

目前大量的研究文献已经描述了如何找到使噪声系数最小的低噪声放大器输入网络的最佳品质因数,但是它们往往遗漏了一个重要的参数——源极电感负反馈低噪声放大器中的栅极电感,它的寄生阻抗为低噪声放大器增加了明显的噪声。本研究课题提出了2种优化方法,这2种方法均满足功率匹配并均衡了晶体管所产生的噪声贡献和栅极寄生阻抗所产生的噪声贡献,从而实现了在栅极电感品质因数、功耗、增益限制下的噪声优化。     

一种预计低噪声GaAs MESFET噪声系数的方法

本文提出了一种预计低噪声GaAs MESFET噪声系数的简便方法.此法只要精确测量器件的总栅源电容C_(gs)、本征跨导gm和总夹断电压W_p,就能求出器件的栅长L、有源层载流子浓度N和厚度a,进而可以预计器件的最小噪声系数NF_(min),故简称为CGW方法.文中还引进了相关栅长L_a的概念,用L_a、N和a预计器件的最小噪声系数与实测值更相符合.本方法还可以具体分析栅长、寄生电阻和GaAs材料质量等因素对器件噪声系数的影响,以便及时调整有关参数,改善器件性能.     

一种K波段高增益低噪声折叠式双平衡混频器

基于130 nm RF CMOS工艺,设计了一种适用于K波段的高增益低噪声折叠式下变频混频器。采用折叠式双平衡电路结构,混频器的跨导级和开关级可以在不同的偏置条件下工作,为优化两级的噪声提供了极大的自由度。采用电流复用技术,混频器的转换增益和噪声系数得以显著改善。后仿真结果表明,该混频器在本振功率为-3 dBm时,实现了27.8 dB的转换增益和7.36 dB的噪声系数。在射频信号为24 GHz处的输入1 dB压缩点P1dB为-18.8 dBm,本振端口对射频端口的隔离度大于60.2 dB。该电路工作于1.5 V的电源电压,总直流电流为12 mA,功耗为18 mW。该混频器以适中的功耗获得了极高的整体性能,适用于低功耗、低噪声24 GHz雷达接收机。     

一种噪声系数为1.4 dB的S波段MMIC低噪声放大器

报道了一种可直接应用于无线接收系统前端的具有较低噪声系数和较高相关增益的MMIC低噪声放大器,该低噪声放大器采用0.50 μm GaAs PHEMT工艺技术制作.电路设计采用两级级联结构,为减小电路面积采用集总参数元件匹配电路,并用ADS软件仿真无源元件寄生效应.电路测试结果表明:在2.8～3.5 GHz 频段内噪声系数低于1.4 dB,同时相关增益大于25 dB,增益平坦度小于0.5 dB,输入输出反射损耗小于-10 dB.     

Noise Figure and Conversion Loss of the Schottky Barrier Mixer Diode

The theory of mixer operation is briefly reviewed and the results presented in graphical form convenient to the designer. In particular, the minimum noise figure, conversion loss, and the source and output impedances are plotted as functions of the pulse duty ratio of the diode current. Emphasis is placed on the pulse duty ratio as a more fundamental parameter for defining mixer operation than the magnitude of the diode voltage which is generally nonsinusoidal. It is shown that Schottky diode mixers should exhibit single sideband noise figures as low as 3 dB at X band when used in conjunction with 1.5 dB noise figure IF amplifiers, provided the diodes have cutoff frequencies higher than 500 GHz.     

Summary of Measurement Techniques of Para-Metric Amplifier and Mixer Noise Figure

Expressions are derived for the noise factor of a frequency mixing circuit under two different operating conditions: 1) single-sideband operation with input only in a band of frequencies at omega/sub 1/; and 2) double-sideband radiometer operation with incoherent inputs in the bands both at frequency omega/sub 1/ and at omega/sub 2/=omega/sub 3/-omega/sub 1/. In both cases, the output is taken only at omega/sub 1/. It is shown that the noise figure for radiometer double-sideband operation is not always 3 db less than for single-sideband operation. It is also shown that it is possible to obtain an output signal-to-noise ratio which is greater than the input signal-to-noise ratio for coherent double-sideband operation. Methods are analyzed for measuring the effective noise temperature of this circuit by using a broad-band noise source.     

高增益、高栅-漏击穿、低噪声微波砷化镓场效应晶体管

本文简要介绍了CX502N型微波砷化镓场效应晶体管的设计、特性与制造。器件采用了新的“积木式”台面结构,减小了栅-漏反馈电容。测试表明,器件具有高增益、高栅-漏击穿及低噪声特性。此外,文中还给出了与CX502N GaAs MESFET类似的器件CX503 GaAs MESFET的一些结果。     

CMOS低噪声放大器的噪声系数优化研究

由于CMOS晶体管的特征尺寸急速的缩放,CMOS晶体管的参数不断改进,使得最新CMOS晶体管获得的噪声系数足够低到足以应用到无线电天文学,因此,在本研究课题中选用CMOS晶体管。目前的低噪声放大器的最小噪声系数是在室温环境下,通过宽带CMOS低噪声放大器的功率匹配来获得。在本研究课题中,CMOS低噪声放大器以共源共栅极结构为基本拓扑结构,主要研究LNA的几种常用的噪声系数优化方法。通过建立小信号模型,对LNA的噪声系数进行分析,得出相应的表达式。     

一种低压低相位噪声的C类VCO

提出了一种低压低相位噪声的C类VCO电路。低压条件下,基于振幅反馈环的C类VCO存在振幅小、相位噪声差的问题,可以通过移除尾电流源、增加低通滤波器等方式来改善相位噪声。基于SMIC 0.18 μm CMOS工艺,采用Cadence Spectre EDA软件对VCO进行仿真。结果表明,当载波频率为2.27 GHz时,在1 MHz频偏处VCO的相位噪声为-126 dBc/Hz,在供电电压为0.9 V时,功耗仅为2.5 mW,FOM值为-189 dBc/Hz。