应用于GPS接收机的宽动态范围连续VGA

针对全球定位系统(GPS)接收机中宽动态范围的要求,提出了一种伪指数近似可变增益放大器(VGA)。该VGA在改进的吉尔伯特单元基础上,采用电压-电流转换电路构成伪指数函数,通过两级级联方式来实现宽线性增益范围,且电路结构对温度不敏感。测试结果表明,当控制电压在0.4~1.45 V变化时,该VGA的线性增益范围为20~80 dB。在50 dB线性增益范围内,增益随温度变化的最大偏差不大于±1.5 dB。     

一种基于g_m/I_D方法设计的可变增益放大器

提出了一种基于gm/ID方法设计的可变增益放大器。设计基于SMIC90nmCMOS工艺模型,可变增益放大器由一个固定增益级、两个可变增益级和一个增益控制器构成。固定增益级对输入信号预放大,以增加VGA最大增益。VGA的增益可变性由两个受增益控制器控制的可变增益级实现。运用gm/ID的综合设计方法,优化了任意工作范围内,基于gm/ID和VGS关系的晶体管设计,实现了低电压低功耗。为得到较宽的增益范围,应用了一种新颖的伪幂指函数。利用Cadence中spectre工具仿真,结果表明,在1.2 V的工作电压下,具有76 dB的增益,控制电压范围超过0.8 V,带宽范围从34 MHz到183.6 MHz,功耗为0.82 mW。     

宽带CMOS可变增益放大器的设计

采用TSMC 0.18μm RF CMOS工艺设计实现了一种对数增益线性控制型的宽带可变增益放大器.电路采用两级结构,前级采用电压并联负反馈的Cascode结构以实现良好的输入匹配和噪声性能;后级采用信号相加式电路实现增益连续可调.同时本文设计了一种新型指数控制电压转换电路,解决了射频CMOS电路中,由于漏源电流与栅源电压通常不为指数关系而造成放大器对数增益与控制电压不成线性关系的难题,实现了可变增益放大器的对数增益随控制电压呈线性变化.芯片测试结果表明,电路在1.8V电源电压下,电流为9mA,3dB带宽为430～2330MHz.增益调节范围为-3.3～9.5dB,最大增益下噪声系数为6.2dB,最小增益下输入1dB压缩点为-9dBm.     

2.4GHz可变增益CMOS跨阻放大器设计

设计了一种2.4 GHz低功耗可变增益跨阻放大器.该放大器为两级放大结构,主要应用于电流模式发射机后端的电流-电压信号转换及放大.第一级放大使用电流复用结构,第二级放大使用共源共栅差分结构.通过控制第一级的跨阻式反馈电阻的大小及第二级偏置电压的大小,在基本不影响输入、输出匹配的情况下,可以得到连续15 dB的增益变化范围.在2.4 GHz及高增益模式下,增益可达18.27 dB,噪声仅为1.061 dB,功耗也仅为6.38 mW.     

宽带CMOS可变增益放大器的设计

采用TSMC0.18μm RF CMOS工艺设计实现了一种对数增益线性控制型的宽带可变增益放大器,电路采用两级结构,前级采用电压并联负反馈的Cascode结构以实现良好的输入匹配和噪声性能;后级采用信号相加式电路实现增益连续可调,同时本文设计了一种新型指数控制电压转换电路,解决了射频CMOS电路中,由于漏源电流与栅源电压通常不为指数关系而造成放大器对数增益与控制电压不成线性关系的难题,实现了可变增益放大器的对数增益随控制电压呈线性变化,芯片测试结果表明,电路在1.8V电源电压下,电流为9mA,3dB带宽为430-2330MHz,增益调节范围为-3.3-9.5dB,最大增益下噪声系数为6.2dB,最小增益下输入1dB压缩点为-9dBm。     

宽带放大器

以AD603型可变增益放大器(VGA)为核心,提出了一种宽带放大器的设计方法,通频带为300 Hz～14 MHz,增益调节范围为10～66 dB,并具有自动增益控制(AGC)的功能,动态范围大于20 dB.整个系统结构简单,界面友好.     

ADI推出两款适用于宽带通信系统的高集成度VGA

ADRF6516在单芯片中集成一对高度灵活、匹配的差分增益放大器和可编程低通滤波器,非常适合基带模数转换器驱动器应用。65 dB的放大器增益控制范围分为两部分:15 dB的数字VGA输入级和50 dB的模拟VGA输出级。利用SPI控制,     

A 0.8–3GHz RF-VGA with 35dB dynamic range in 0.13μm CMOS* Qin Xi(秦希), Huang Xingli(黄杏丽), Qin Yajie(秦亚杰), Hong Zhiliang(洪志良)?

本文提出了一种使用0.13μm CMOS工艺实现的宽带可变增益放大器（VGA）结构。为了优化该VGA的噪声性能,一个具有15dB固定增益、采用有源反馈结构的预放大器被用来作为第一级,之后采用级联的改进型Cherry-Hooper放大器提供增益调节,双反馈环路在这里被用来扩展Cherry-Hooper放大器的带宽。负容性中和和电容源极退化技术分别被用来进行密勒效应补偿和直流失调取消。测试结果显示,该VGA达到35dB增益调节范围,其高端3dB带宽大于3GHz,在最低增益时,1dB压缩点为-29dBm,在最高增益时,噪声系数达到9dB。该VGA（不包括输出缓冲器）在1.2V电源电压下消耗32mW功率,占用芯片面积为0.48mm₂。     

应用于DVB-T调谐器的CMOS可变增益中频放大器设计

采用TSMC 0.18μm RF CMOS工艺设计了一种适用于DVB-T调谐器的可变增益中频放大器。该放大器以信号相加式单元为主体电路,采用三级级联结构,实现了对数增益随控制电压连续、近似线性地变化和51dB的增益动态范围。仿真结果表明,在1.8V电源电压下,电路工作电流为30mA,3dB带宽为2-156MHz。增益调节范围为7.4-58.4dB,噪声系数小于8.6dB,输出三阶互调点大于0.6dBm。     

一种10 Gbit/s光接收机前置放大器

基于0.18 μm BiCMOS工艺,设计了一种适用于光纤通信的10 Gbit/s光接收机前置放大器。电路由跨阻放大器、两级可变增益放大器、缓冲器、直流偏移消除电路、峰值探测器和自动增益控制环路组成。跨阻放大器采用并联-并联负反馈结构,在满足增益、带宽要求前提下实现低噪声特性。后级放大器引入了增益可变控制,获得宽输入动态范围,同时采用电容简并技术提升带宽。版图后仿真结果表明,在小信号光电流输入下,放大器的差分跨阻增益为10.7 kΩ,-3 dB带宽为7.4 GHz,平均等效输入噪声电流密度为16.9 pA/Hz。可调增益范围在25.2~80.6 dBΩ内,输入动态范围超过40 dB。在3.3 V电压下,静态功耗为166 mW,版图尺寸为764 μm540 μm。     

A single-stage variable-gain amplifier with 70-dB dynamic range for CDMA2000 transmit applications

A variable-gain amplifier (VGA) circuit is presented with a gain range of more than 70 dB in a single stage. Vertical stacking of multipliers in a single-stage VGA results in a considerable saving of power, which is a prime requirement in cellular systems. The gain-in-dB is a linear function of the control voltage and has excellent stability over temperature. The amplifier is a part of a code-division multiple access cellular transmit integrated circuit, and provides good linearity and noise characteristics over a wide range of IF frequencies. The circuit is fabricated in a 30-GHz f/sub t/ BiCMOS technology and consumes 8 mA at 2.7 V.     

具有温度补偿及dB线性增益控制的单级宽范围CMOS可变增益放大器

提出了一种新颖的宽范围CMOS可变增益放大器结构.利用可变跨导和新颖的可变输出电阻,基于单独可变增益级的放大器可提供80dB的宽范围调节.同时控制电路的设计完成了温度补偿及dB线性增益特性,实现在整个温度及增益调节范围内绝对增益误差小于±1.5dB.基于0.25μm CMOS工艺验证表明,放大器可提供64.5dB的增益变化范围,其中dB线性范围为55.6dB.输入1dB压缩点为-17.5到11.5dBm,3dB带宽为65MHz到860MHz,2.5V电源供电下功耗为16.5mW.     

A 2.7-V SiGe HBT variable gain amplifier for CDMA applications

A monolithic SiGe HBT variable gain amplifier with high dB-linear gain control and high linearity has been developed for CDMA applications. The VGA achieves a 30-dB dynamic gain control with a control range of 0-2.7 Vdc in 824-849 MHz band. The maximum gain and attenuation are 23 dB and 7 dB, respectively. Input/output VSWRs keep low and constant despite change in the gain-control voltage. At a low operation voltage of 2.7 V, the VGA produces a 1-dB compression output power of 13 dBm and /spl plusmn/885-kHz ACPR of -57 dBc at a 5-dBm output power.     

Wideband high dynamic range CMOS variable gain amplifier for low voltage and low power wireless applications

A high frequency CMOS variable gain amplifier (VGA) employing a new gain stage cell is proposed. A design technique based on the proposed VGA enables enhancement of its operating frequency up to about 350 MHz with a gain control range of 84 dB. The power consumption of the VGA implemented using a 0.18 /spl mu/m CMOS standard process is about 3 mA at 1.8 V supply voltage.     

A monolithically integrated HEMT-HBT low noise high linearityvariable gain amplifier

We report on a 1-6 GHz HEMT-HBT three-stage variable gain amplifier (VGA), which is realized using selective molecular beam epitaxy (MBE). The VGA integrates an HEMT low noise amplifier with an HBT analog current-steer variable gain cell and output driver stage to achieve a combination of low noise figure, wide gain control, and high linearity. The HEMT-HBT VGA MMIC obtains a maximum gain of 21 dB with a gain control range >30 dB, a minimum noise figure of 4.3 dB, and an input IP3 (IIP3) greater than -4 dBm over 25 dB of gain central range. By integrating an HEMT instead of on HBT preamplifier stage, the VGA noise figure is improved by as much as 2 dB compared to an all-HBT single-technology design. The HEMT-HBT MMIC demonstrates the functional utility and RF performance advantage of monolithically integrating both HEMT and HBT devices on a single substrate     

一种具有温度补偿的宽带CMOS可变增益放大器

设计实现了一个具有温度补偿的宽带CMOS可变增益放大器,该可变增益放大器的核心电路由三级基于改进型Cherry-Hooper结构的可变增益单元级联而成,并通过一种温度系数增强的且可编程的偏置电路和增益控制电路对可变增益放大器的增益进行温度补偿。采用中芯国际0.13μm CMOS工艺流片,测试结果表明可变增益放大器的可变增益范围为-13～27dB,经过温度补偿后,在相同增益控制电压下其增益在0～75°C温度范围内的变化范围不超过3dB。可变增益放大器的3dB带宽为0.8～3GHz,输入1dB压缩点为-50～-21dBm,在1.2V电压下,功耗为21.6mW。     

A low-distortion CMOS IF VGA with linear-in-dB control and temperature compensation

A CMOS intermediate-frequency (IF) variable-gain amplifier (VGA) is presented in this paper. A transconductance linearization scheme is proposed for the VGA core based on a signal-subtracting structure to achieve low distortion. Temperature-independent decibel-linear gain control characteristic is achieved by an exponential voltage generator based on transfer characteristics of differential pair. The whole VGA, including a highly-linear output stage, is fabricated in 0.25 μm CMOS technology. Measurements show that the VGA provides a total gain control range of 43 dB with less than 1.2 dB error over 0–80°C, and a constant 3-dB bandwidth of 100 MHz. The third-order intermodulation (IM3) distortion at differential output of 2 V_PP is better than −55 dB. The VGA dissipates 22.6 mA averagely from 3.3 V supply, and occupies approximately 0.53 mm².     

Wideband CMOS variable gain amplifier with decibel-linear gain control characteristic

This paper presents a wideband variable gain amplifier (VGA) featuring a decibel-linear gain control characteristic. The decibel-linear gain control function is realized using two VGA cells and a control signal converter. The bandwidth is extended using cascode architecture together with active inductive load. To achieve small parasitic and low area, direct current (DC) coupling is adopted in the circuit while a DC offset cancellation circuit (DCOC) is introduced to cancel the DC offset. Fabricated in a 0.18 μm complementary metal oxide semiconductor (CMOS) process, the chip occupies an area of 0.53 mm × 0.48 mm (including pads) and draws a total current of 9 mA from a 1.8 V supply. The measurement results show that the gain of the VGA varies from -40 dB to 18 dB while the control voltage varies from 0 to 1.8 V, resulting in a total gain control range of 58 dB. The 3 dB bandwidth of the VGA is larger than 260 MHz at maximum gain.     

A comprehensive,adjustable approach for linearizing and broadening the gain characteristic of variable gain amplifiers

In this paper a comprehensive approach is presented to linearize and adjust gain characteristic of variable gain amplifiers (VGAs). It is also capable of increasing the output linear dynamic range of VGAs and modifying variation range of control voltage. The approach is able to change the voltage gain characteristic of an amplifier, even after fabrication, to a desired one by means of a digital control signal and a digital to analog converter. Using this approach, the gain of basic differential amplifier is controlled by two different predistorters, and adjustable dB-linear characteristics in range of greater than 60 dB are achieved. The approach, also, is applied to two conventional VGAs, the gain characteristic of first VGA is linearized, and in the second VGA, the linear dynamic range is expanded about 26 dB. The controller uses 1.2 V voltage supply, and simulations are done using 0.13 µm CMOS process model. The other characteristics of each mode of control are reported completely.