A class-E power amplifier for wireless biomedical systems

This letter presents the design, implementation and experimental results of a class-E power amplifier (PA) suitable for wireless biomedical sensor nodes (WBSNs) integrated into a wireless body area network (WBAN). A self-biased inverter is used as a preamplifier stage to provide a 50 %-duty-cycle square wave to drive the class-E PA. The design (PA with the preamplifier), which is fabricated in a 0.18-μm CMOS technology, achieves 40.2 % drain efficiency while output power is 14.7 dBm at 433 MHz under 1.2-V supply, as demonstrated by the experimental results.     

Design of broadband transimpedance amplifier for optical communication systems

This paper describes the design and analysis of broadband transimpedance amplifiers (TIAs) based on Regulated Cascode (RGC) configuration. The focus is to deal with bandwidth restriction occurring in optical receivers coming from TIA input parasitic capacitances. Despite the conventional method for broadband RGC TIA design that a ladder matching network is employed to isolate the input capacitance of TIA and the photodiode capacitance, the proposed TIA eliminates the effects of these parasitic components by absorbing them in a T-matching network. The conventional broadband RGC TIA is analyzed and the disadvantages of the ladder matching network is demonstrated in a TIA design example. The proposed RGC TIA is simulated on 0.18-μm standard RF CMOS process. The simulation results presented show that the Gain-Bandwidth product (GBW) is extended by a larger factor compared to that of the conventional broadband RGC TIA while the biasing conditions and the value of the photodiode capacitance are considered the same.     

Very compact thin power amplifier module for gigahertz-bandcellular systems

A power amplifier module for gigahertz-band cellular phone systems. Developed using a build-up structure based on MCM-D technology and all planar passive circuit components, is investigated. It is shown that the very compact thin module can be incorporated with a thickness of <1 mm and a volume of <0.1 cc     

A temperature-insensitive erbium-doped fiber amplifier for terrestrial wavelength-division-multiplexing systems

We have evaluated a variation in the temperature dependence of an erbium-doped fiber gain spectrum by a pump wavelength in the 980-nm band for the first time. By optimizing both the pump wavelength in the 980-nm band and a temperature-sensitive gain flattening filter, the gain change of an erbium-doped fiber amplifier was successfully suppressed to 0.18 dB/sub pp/ in the temperature range between 0/spl deg/C and 65/spl deg/C and the wavelength range of 37.0 nm.     

A programmable instrumentation amplifier for 12-bit resolution systems

Describes the design of and experimental results obtained from a monolithic gain-programmable instrumentation amplifier that attains performance compatible with 12-bit or higher resolution data acquisition systems. Nonlinearity is held to a 0.01 percent worst-case level over the -25 to 85/spl deg/C temperature range for gains of 1-1000, independent of process variations. Input and output voltage noise and offset drift are also reduced to low levels. A novel input overvoltage protection scheme is also described. The amplifier is fabricated on a standard-beta junction isolated bipolar process that has in addition process-compatible ion implanted JFETs and silicon-chromium thin-film resistors.     

面向6G的拉曼微结构光纤放大器设计

为了满足6G系统对未来光通信网络的要求,利用掺 GeO₂微结构光纤设计了一种多泵浦拉曼光纤放大器,该方案能够解决适用于6G系统需求的 拉曼光纤放大器中谱宽窄、输出增益低且不平坦的问题。在理论上,运用四阶龙格-库塔法 对经典拉曼耦合波微分方程进行求解;在结构上,通过合并两对具有相同波长的泵浦光,来 减少泵浦个数、简化结构,同时采用级联两段微结构光纤的方法,使信号光增益在拉曼放大 器的输出端实现前放大,后补偿。实验结果表明,在100 nm的谱宽范 围内,放大器的平均增益高达35.72 dB,增益波动小于±0. 43 dB。     

Nonlinear amplifier effects in communications systems

This paper introduces a figure-of-merit to investigate tradeoffs between amplifiers and modulation waveforms in complex digital communications systems. Class-AB amplifiers are investigated with a variety of modulation schemes to better understand the relations between amplifier efficiency, amplifier distortion, signal in-band and adjacent channel interference, and power consumption. The goal is to better understand the tradeoffs needed to design low-energy communications systems     

A wide-band CMOS read amplifier for magnetic data storage systems

Circuit techniques for a CMOS amplifier suitable for read waveform signal processing in high-speed disk drives are described. A 30-MHz low-noise preamplifier with a gain of 100 was designed in 3-μm CMOS, capable of being driven by an inductive source, and producing an equivalent input noise voltage spectral density of 2 nV/√Hz. This, with other recent developments, makes it possible to conceive of entirely CMOS read/write signal-processing ICs     

Monolithically integrated waveguide-MSM detector-HEMT amplifier receiver for long-waveguide lightwave systems

The first demonstration is reported of a long-wavelength receiver that monolithically integrates an InGaAsP waveguide, an InAlAs-InGaAs metal-semiconductor-metal (MSM) detector, and an InAlAs-InGaAs high-election-mobility transistor (HEMT) amplifier. External responsivities in response to a guided signal of 0.43 and 0.5 A/W were recorded, respectively for a 150- and a 300- mu m-long detector integrated with an InGaAsP waveguide. This corresponds to an internal quantum efficiency of about 95% after taking account of the combined external losses such as insertion loss between waveguide and fiber and propagation loss in the waveguide. A pulse response of 200 ps. corresponding to a bandwidth of about 820 MHz, was measured at the output of the HEMT amplifier. The receiver represents a major advance toward achieving high-performance integrated receiving components for long-wavelength lightwave systems.<>     

A low-noise gain-tunable amplifier for large array biopotential recording systems

This paper presents a low-noise gain-tunable biopotential amplifier that is designed based on a folded-cascode structure. Sub-threshold and self-biasing techniques are employed to achieve a low-noise and low-power amplification. With a bias-current tuning block, the gain of the proposed biopotential amplifier can be precisely adjusted. Designed in a standard 0.13 μm CMOS process, the proposed amplifier provides a 5.9 kHz bandwidth and 30.1 dB gain with 732 nW power. The input-referred noise over the entire bandwidth is 4.3 μV _rms , equivalent to a noise-efficiency factor of 2.48.     

Semiconductor optical amplifier for wavelength conversion in subcarrier multiplexed systems

The fabrication and performance of a InGaAsP-InP semiconductor optical amplifier for wavelength conversion in subcarrier multiplexed system is described. The amplifier is of the buried facet design and has polarization and reflectivity gain ripple of less than 1 dB. Using subcarrier multiplexing, multiple 50-Mb/s data streams at a wavelength of 1.553 /spl mu/m are infected into the amplifier. The gain nonlinearity of the amplifier transfers the data to a different wavelength of light simultaneously injected into the amplifier. Error free retrieval of subcarrier multiplexed data has been demonstrated for the wavelength converted output. The small signal bandwidth of the wavelength conversion process is 5 GHz. Calculation suggests that higher bandwidth is feasible at higher input powers at the expense of lower modulation transfer during wavelength conversion.     

A GaAs monolithic 6 GHz low-noise amplifier for satellite receivers

A design approach and accurate modeling techniques developed to realize a GaAs monolithic, 6-GHz, two-stage, low-noise amplifier (LNA) with a measured 1.7 dB noise figure and associated 21 dB gain are discussed. This self-biased LNA design, with chip dimensions of 80 mil×135 mil, utilizes an ion-implantation FET model which predicts measured in-band amplifier gain to within 0.5 dB and peak frequency response to within 4%. The derived noise parameter estimation process, which uses a Gaussian elimination technique to predict the measured noise figure to within 0.2 dB, reduces a set of complex, binomial equations to simple relationships which are easily programmable. A deep-recessed gate realization of this LNA design demonstrates that LNA low-noise performance is achievable under FET saturated drain current conditions     

一款应用于Wi-Fi 6E设备的GaAs HBT功率 放大器

针对WIFI 6E频段的设备需求,设计了一款工作在5.9 GHz～7.2 GHz的宽带砷化镓异质结双极型晶体管（GaAs HBT）功率放大器。功率放大器为三级放大拓扑结构,采用自适应偏置电路结构解决HBT晶体管在大功率输入下偏置点变化及自热效应引起增益及线性度恶化的问题。测试结果表明,在5.9 GHz～7.2 GHz频段内,功率放大器增益>27 dB,输出饱和功率>1 W,附加效率>24 %,芯片面积：1.24 mm×1.27 mm。     

超长距波分复用系统中混合光放大器的研究

采用理论分析和软件仿真的方法,研究了级联混合光放大器在超长距波分复用系统中的应用,在讨论单跨距混合光放大器工作原理的基础上,对级联混合光放大器的光信噪比及增益平坦等特性进行分析,设计了适用于ULH系统的高信噪比、动态增益平坦的混合光放大器系统,并结合实际的ULH应用案例进行了建模仿真.     

An erbium-doped tellurite fiber amplifier for WDM systems with dispersion-shifted fibers

This letter investigates the feasibility of an erbium-doped tellurite fiber amplifier (EDTFA) with a 1581- to 1616-nm amplification band for a wavelength-division-multiplexing transmission system in the L-band that employs dispersion-shifted fiber (DSF). A 10-Gbit/s, 40-channel-transmission from 1581 to 1616 nm in the L-band, where EDTFA's are employed as a post-amplifier, repeaters, and a pre-amplifier, is error-free through a 320-km DSF. The EDTFA can increase both the transmission capacity and the allowable maximum input power launched into a DSF.     

Nonlinear amplifier optimal characteristics shaping for self-oscillating systems of vibrofrequency densometers

It is considered methods of nonlinear amplifier optimal characteristics shaping for self-oscillating systems of vibrofrequency densometers. This method allows to decrease essentially non-stability of self-oscillation mechanical resonators in comparison with “saturation” type characteristic of and analysis of high harmonics at the output of nonlinear amplifier on self-oscillation frequency.     

Highly nonlinear fiber-based lumped fiber Raman amplifier for CWDM transmission systems

The highly nonlinear fiber (HNLF)-based lumped fiber Raman amplifiers (LRAs) for four- and eight-channel coarse wavelength division multiplexing (CWDM) transmission systems have been investigated. By using the developed LRA, the four-channel CWDM transmission over conventional single-mode fiber (SMF) with the length of 150 km has been successfully achieved.     

Optical time domain reflectometry on optical amplifier systems

The use of optical time-domain reflectometry (OTDR) on long-span fiber transmission systems containing in-line optical amplifiers is discussed. Having identified the specific requirements for OTDR equipment, measurements were carried out on systems of up to 300 km in length, containing three semiconductor laser amplifiers. The results demonstrate that OTDR can be used not only for fault location on fiber links several hundred kilometers in length but also as an alternative to standard system supervisory techniques, thus providing the potential for minimizing the hardware in the optical amplifier stages of future long-span fiber optic transmission systems     

Transmission distance of in-line amplifier systems withgroup-velocity-dispersion compensation

Group-velocity dispersion (GVD) compensation in in-line amplifier systems is evaluated from the viewpoint of improving the transmission distance. The nonlinear Schrodinger equation, which simulates signal propagation in optical fibers, is numerically evaluated to clarify the optimum configuration for GVD compensation. It is shown that the optimum amount of GVD compensation is about 100% of the GVD experienced by the transmitted signal. The optimum compensation interval is found to be a function of the bit rate, signal power, and dispersion parameter. For dispersion parameter values ranging from about -0.1 ps/nm/km to -10 ps/nm/km, and an amplifier noise figure of about 6 dB, the optimum compensation configuration can eliminate the GVD from in-line amplifier systems, thus improving transmission distances to those limited by self-phase modulation and higher-order GVD     

An analytical framework for CDMA systems with a nonlinear amplifier and AWGN

The design of code-division multiple-access (CDMA) transmission systems for satellite communications requires an appropriate consideration of the distortion effects due to on-board nonlinear amplification. The aim of this paper is to provide an analytical framework for the evaluation of the in-band nonlinear distortion effects on the performance of CDMA systems. Both synchronous systems with orthogonal codes and asynchronous systems are considered. It is first shown that, when the users accessing the channel have the same power and their number is sufficiently large, the nonlinear distortion in the decision variables at the receiver can be simply described by a complex scale factor, which depends on the high-power-amplifier (HPA) characteristics only, and an additive noise, which is uncorrelated to the useful signal. Moreover, an analytical formulation of the bit error probability and the total degradation as a function of the output back-off and number of users is given. In the results, which are obtained for three classes of HPA models (i.e., the traveling wave tube amplifier, the solid-state power amplifier, and the amplifier with ideal predistortion), the performance and the capacity of power-limited systems is also discussed.