Highly linear and low noise differential bipolar MOSFET down-converter in CMOS process

A highly linear, low noise differential down-converter employing a new linearisation technique derived from composite transistors, i.e. nMOSFET and vertical NPN BJT, is proposed and implemented in a 0.18 μm CMOS technology. It draws 1 mA from a 2.5 V supply voltage and has a voltage gain of 13 dB, a double-sideband noise figure of 9.5 dB, an IIP2 of more than 49 dBm, and an IIP3 of 6.5 dBm.     

Robust derivative superposition method for linearising broadband LNAs

A linearisation methodology for broadband low noise amplifiers (LNAs) is considered. The proposed scheme is composed of the main transistor operating in strong inversion healed by a couple of auxiliary transistors operating in triode and subthreshold regions. The nonlinearities of these transistors graciously and efficiently compensate each other, improving main transistor linearity by over 10 dB over all corners for input signals as large as -14 dBm. Power consumption increases by 6% while frequency response and input impedance are almost not affected because the compensating circuits are quite small compared with the main device. Simulation results show that the compensated LNA implemented in Jazz-Semiconductor 0.18 mum CMOS technology has a gain of 11.3 dB, IIP3 = 18.4 dBm, BW = 3.6 GHz while drawing 7.4 mA from a 2.4 V supply voltage.     

Linearisation of RF PA by even-order nonlinear baseband signal processed in digital domain

This paper represents, for the first time, the linearisation method of RF power amplifiers, which is based on using the second- and fourth-order nonlinear signals shaped by digital signal processing in a baseband domain. The linearisation signals are generated by the second- and fourth-order nonlinear modifications of the baseband signal in the proposed manners. The composite second- and fourth-order linearisation signals modulate carrier second harmonics, and the modulated signals are then driven to the gate and drain of the amplifier transistor. The linearisation effects of the proposed method are evaluated on a single stage power amplifier for the simulated QAM and OFDM digitally modulated signals at diverse input power levels up to the 1 dB compression point. Moreover, the FPGA implementation of a system for the generation and processing of the fundamental signal, and the second-order linearisation signals is presented in the paper, and the proposed technique is verified for the generated QAM signal. In addition, the linearisation of the two-way asymmetrical Doherty amplifier is performed in the experiment by using software defined radio platforms for synthesising the fundamental signal and the second-order linearisation signals.     

Linearised distributed amplifier with low linearisation loss

A four-element linearised distributed amplifier operating between 0.8 and 2.2 GHz is presented. The parallel diode linearisation technique is applied to a distributed amplifier resulting in a 14 dB gain linearised amplifier. The addition of the lineariser, gave a reduction in gain of less than 1 dB with a 7-12 dB reduction in spectral regrowth for the first sidelobe.     

Linearisation of a cascaded system of analogue optical links

We describe a linearisation technique suitable for compensation of nonlinearities in a cascaded system of analogue optical links. Experimentally, we have observed an improvement of more than 30 dB in 2nd-order distortion, reducing distortion to ?53 dB in a cascaded system of four optical transmitter/receiver modules.     

5-GHz SiGe HBT monolithic radio transceiver with tunable filtering

A wide-band CDMA-compliant fully integrated 5-GHz radio transceiver was realized in SiGe heterojunction-bipolar-transistor technology with on-chip tunable voltage controlled oscillator (VCO) tracking filters. It allows for wide-band modulation schemes with bandwidth up to 20 MHz. The receiver has a single-ended single-sideband noise figure of 5.9 dB, more than 40 dB on-chip image rejection, an input compression point of -22 dBm, and larger than 70 dB local-oscillator-RF isolation. The phase noise of the on-chip VCO is -100 and -128 dBc/Hz at 100 kHz and 5 MHz offset from the carrier, respectively. The transmitter output compression point is +10 dBm. An image rejection better than 40 dB throughout the VCO tracking range has been demonstrated in the transmitter with all spurious signals 40 dB below the carrier. The differential transceiver draws 125 mA in transmit mode and 45 mA in receive mode from a 3.5-V supply     

适于InGaAsP光放大器偏振不灵敏的增益介质

研制了适于InGaAsP光放大器偏振不灵敏的增益介质 ,采用有源区内交替的张应变和压应变排列的混合应变量子阱结构 ,器件做成带有倾角的扇形。实验中发现该结构既抑制了激射又改善了器件的偏振灵敏性 ,实现了偏振灵敏度小于 0 5dB ,10 0mA偏置时可达 0 1dB。在较大的电流范围内 ,峰的半高全宽 (FWHM)为 4 0nm。     

A Four‐Channel Laser Array with Four 10 Gbps Monolithic EAMs Each Integrated with a DBR Laser

A distributed Bragg reflector (DBR) laser and a high speed electroabsorption modulator (EAM) are integrated on the basis of the selective area growth technique. The typical threshold current is 4 to 6 mA, and the side mode suppression ratio is over 40 dB with single mode operation at 1550 nm. The DBR laser exhibits 2.5 to 3.3 mW fiber output power at a laser gain current of 100 mA, and a modulator bias voltage of 0 V. The 3 dB bandwidth is 13 GHz. A 10 Gbps non‐return to zero operation with 12 dB extinction ratio is obtained. A four‐channel laser array with 100 GHz wavelength spacing was fabricated and its operation at the designed wavelength was confirmed.     

A Wavelength Tunable DBR Laser Integrated with an Electro-Absorption Modulator by a Combined Method of SAG and QWI

We report a wavelength tunable electro-absorption modulated DBR laser based on a combined method of SAG and QWI.The threshold current is 37mA and the output power at 100mA gain current is 3.5mW.When coupled to a single-mode fiber with a coupling efficiency of 15%,more than a 20dB extinction ratio is observed over the change of EAM bias from 0 to -2V.The 4.4nm continuous wavelength tuning range covers 6 channels on a 100GHz grid for WDM telecommunications.     

基于SAG和QWI结合技术的电吸收调制器与可调谐DBR激光器的单片集成

报道了基于选择区域生长和量子阱混杂结合技术的电吸收调制器与可调谐DBR激光器的单片集成.集成器件显示出了良好的静态特性:阈值电流为37mA;100mA激光器增益区偏置电流下,直流输出功率为3.5mW;当使用单模光纤耦合(耦合效率15%),调制器偏压在0～-2V之间时,静态消光比大于20dB;波长调谐范围为4.4nm,覆盖了6个100GHz间隔的WDM信道.     

Microwave modulation by amorphous-semiconductor switches

Microwave modulation has been achieved by using thin-film amorphous-semiconductor switches made of ternary chalcogenides. X-band microwaves were modulated by a threshold switch at frequencies varying from 100 Hz to 1 MHz, with modulation efficiencies comparable to siliconp?i?n diodes. The insertion loss was 0.5 to 0.6 dB and the isolation was 18 dB at 100 mA operating current. Possible applications this method are discussed.     

Junction-current-confinement planar 1.3 ?m InGaAsP/InP surface-emitting LEDs

A new high-power high-efficiency 1.3 ?m surface-emitting InGaAsP/InP LED has been obtained by utilising a reverse-biased InP homojunction to achieve efficient confinement of injected current into the InGaAsP emitting area. The devices are grown by a two-step LPE process. At 20 mA, output powers >400 ?W are obtained; over 1.5 mW is obtained at 100 mA. A 3 dB modulation frequency >60 MHz is obtained at 115 mA.     

Highly uniform operation of high-performance 1.3-μm AlGaInAs-InPmonolithic laser arrays

We describe the fabrication of monolithically integrated 1×12 arrays of 1.3-μm strain-compensated multiquantum-well AlGaInAs-InP ridge lasers. The laser array shows highly uniform characteristics in threshold current, slope efficiency, and lasing wavelength with a standard deviation of 0.08 and 0.27 mA, 0.012 and 0.007 W/A, and 0.59 and 0.57 nm, respectively, at 20°C and 100°C. Besides, each laser on the array exhibits a low threshold current of 8 mA at 20°C and 21 mA at 100°C, a characteristic temperature of 92 K, and a slope efficiency drop of 0.7 db between 20°C and 80°C. A low thermal crosstalk of less than -4 dB can be obtained from one diode as the injected current of other elements is increased to 70 mA. Also, each laser on the array has a negligible degradation after a 24-hr burn-in test at 80 mA and 100°C. An expected lifetime of more than 20 years is estimated for the lasers when operating at 10 mW and 85°C. The lasers have a small-signal modulation bandwidth of about 9 GHz at 25°C and a low relative intensity noise of -155 dB/Hz without an isolator at 2.5 GHz. It can transmit a 2.5-GHz signal to 50 km through standard single-mode fiber and to 308 m through multimode fiber, with a clear eye opening in OC-48 data-rate tests     

Long-wavelength InGaAsP/InP distributed feedback lasersincorporating gain-coupled mechanism

Successful operation of long-wavelength InGaAsP low-threshold-current gain-coupled DFB lasers was demonstrated by using an InGaAsP quaternary grating that absorbs the DFB (distributed feedback) emission. The amount of gain (loss)-coupling is controlled by the composition (bandgap) and thickness of the grating quaternary and the InP-spacer layer between the grating and the active layer. With optimally designed lasers, CW (continuous-wave) threshold currents were 10-15 mA (250-μm cavity, as-cleaved), slope efficiency was ~0.4 mW/mA (both facets) and SMSR (side-mode suppression ratio) was as high as 52 dB. The laser operated in the same DFB mode with SMSR staying ~50 dB throughout the entire current range. At 100°C, the CW threshold current stayed low, ~50 mA, and SMSR was ~40 dB. Results also indicate that the presence of gain-coupling removes the degeneracy in lasing wavelength     

Integration of a laser diode with a polymer-based waveguide forphotonic integrated circuits

The fabrication and characterization of BRS lasers monolithically integrated with butt-coupled polymer-based buried strip waveguides is presented. Threshold currents of lasers with one cleaved and one etched mirror facets are 15-18 mA and waveguide output powers are in excess of 5 mW at 100 mA laser driving currents and for 600 μm long waveguides. The device exhibits a total waveguide insertion loss less than 5 dB. The integrated device is potentially suitable as a building-block for photonic integrated circuits     

Linearised mixer using frequency retranslation

A new linearisation technique using frequency retranslation for generating an error signal to predistort the input of a nonlinear mixer is presented. Results from a two-tone-test at 920 MHz yields a 25 dB reduction in the distortion products and also minimal adjacent channel interference was observed with a π/4 differential quadrature phase shift keying modulated carrier     

Phase-shift modulation technique for the linerisation of analogue optical transmitters

A phase-shift modulation technique is described for the linearisation of light sources in fibre-optic transmission systems. A 25 dB reduction in the 2nd-harmonic distortion has been achieved in specially fabricated GaAlAs double-heterostructure light-emitting dioded (l.e.d.s) compared with the distortion levels typical of conventional l.e.d.s.     

The nonlinearity of high-radiance light-emitting diodes

Distortion measurements have been performed on a series of Burrus-type LED's as a function of device structure, type of dopant, and dopant concentration in the active layer of devices. The results of measurements show that the total harmonic distortion (THD) in double heterostructure LED's is relatively insensitive to the type and amount of dopant in the active layer provided the ratio of the active layer thicknessdto diffusion lengthLis less than one. Ford/L > 1an improvement in THD is observed by about 20 dB to a value of -50 dB at 100 mA dc and 100 mA peak-to-peak modulation currents. The improvement in the linearity is attributed to the reduction of the influence of the heterostructure boundary on the minority carriers in the active layer of LED's.     

433MHz ASK接收机射频前端电路设计

设计了一款应用在433MHz ASK接收机中的射频前端电路。在考虑了封装以及ESD保护电路的寄生效应的同时,从噪声、匹配、增益和线性度等方面详细讨论了低噪声放大器和下混频器的电路设计。采用0.18μm CMOS工艺,在1.8V的电源电压下射频前端电路消耗电流10.09 mA。主要的测试结果如下:低噪声放大器的噪声系数、增益、输入P1dB压缩点分别为1.35 dB、17.43 dB、-8.90dBm;下混频器的噪声系数、电压增益、输入P1dB压缩点分别为7.57dB、10.35dB、-4.83dBm。     

质子注入平面掩埋条形高频DFB激光器

报道了采用质子注入制作平面掩埋条形高频ＤＦＢ激光器。质子注入提高了限制层对电流的限制作用,并减小了限制层的寄生电容;ＤＦＢ激光器的斜率效率由注入前的０．１４７ｍＷ／ｍＡ提高到０．２１６ｍＷ／ｍＡ;电容测试结果表明：质子注入使ｐｎｐｎ结构的势垒电容明显减小,激光器的寄生电容由注入前的约１００ｐＦ降至注入后的６ｐＦ;激光器的３ｄＢ调制宽带由注入前的５００ＭＨｚ提高到５．６６ＧＨｚ。高温老化筛选结果表明