20 GHz bandwidth low-noise HEMT preamplifier for optical receivers

A broadband, low-noise HEMT preamplifier is designed for very high-speed fibre-optic transmission systems. A 20 GHz 3 dB down bandwidth and 7.6 pA/√(Hz) averaged input equivalent noise current density from 100 MHz to 18 GHz are achieved using inductor peaking techniques and low stray capacitance chip resistors     

Variable bandwidth and tunable centre frequency filter usingtransversal-form programmable optical filter

The authors report the realisation of an integrated-optic variable bandwidth and tunable centre frequency filter using a transversal-form programmable optical filter with 32 taps. The bandwidth is varied from 44 to 84 GHz with a fixed centre frequency. Also, the centre frequency is tuned over 105 GHz with a fixed bandwidth     

GaAs monolithic integrated optical preamplifier

A GaAs monolithic integrated optical preamplifier has been developed based on the transimpedance principle. By associating the amplifier with an external p-i-n diode, a sensitivity of -38 dBm was measured at 140 Mbits/s and 10^-9error rate with a signal wavelength of 1.3 μm. A TiWSiN-integrated technology was used to realize larger than 100-kω feedback resistors and gate leakage could be minimized by improving Schottky contact deposition and employing selective implantation. The optimization details of the FET and resistor elements, as well as the design techniques for integrated transimpedance amplifiers are presented.     

载波调制激光雷达滤波带宽的半实物仿真平台

将脉冲激光调制成更窄脉宽的脉冲串,并作为激光雷达信源信号用于水下探测,在接收端采用窄带滤波器的方案被证明可以有效抑制海水后向散射对水下探测的影响。在实际应用中,在调制频率一定的情况下,接收端滤波器带宽设计直接决定系统对海水后向散射抑制能力。在研究海水水质参数与脉冲激光频率展宽的基础上,构建海洋载波调制脉冲激光雷达半实物平台进行仿真实验研究。半实物仿真表明,随着滤波带宽增大,对比度提升呈现出了先增大后缓慢下降的趋势。最后通过实验结果的对比分析给出了一种滤波器带宽设计方法。     

System performance of optical fibre preamplifier

An optical fibre amplifier has been used as an optical preamplifier for a PIN detector-based receiver. A maximum amplifier gain of 22 dB has been measured and, at this gain with no additional optical filtering, an improvement of 10.5 dB in receiver sensitivity has been achieved.<>     

Nonlinear feedback preamplifier for optical trigger circuits

A nonlinear preamplifier system to improve the performance of a zero-crossover optical trigger circuit is presented. The network is based on a low-noise operational amplifier with a Zener diode feedback. It is proposed to exploit the nonlinear characteristic of this network to reduce timing measurement uncertainty. Accordingly the circuit has been developed and tested in operation.     

Ultrawide bandwidth optical receivers

Low-noise p-i-n/HEMT optical receivers with bandwidths in excess of 16 GHz have recently been developed using advanced microwave design and packaging techniques. Here, state-of-the-art receiver technology, including design tradeoffs and implementation techniques for this class of ultrawide bandwidth receiver, is discussed. Some directions for future research are explored     

带AGC的CMOS光接收机前置放大器的设计

设计了一种带有自动增益控制电路（AGC）的动态范围较宽的互补型金属氧化物半导体（CMOS）光接收机跨阻前置放大器（TIA）。该放大器的工作电压为3.3V。采用0．25μm CMOS工艺库仿真，结果表明：小信号输入时，跨阻增益可达76kΩ，单端输出信号在输入信号为0dBm时为281mV。     

Transimpedance optical preamplifier having a common-collector front end

A simple PIN photodiode-bipolar transistor (PIN-BJT), direct-coupled, transimpedance, optical preamplifier suitable for fabrication in monolithic IC form is described. The preamplifier basically consists of a common-collector, common-emitter configuration with shunt feedback. Measurements indicate that the receiver is capable of a sensitivity of ?35.8 dBm at 140 Mbit/s for an error rate of 10?9.     

一种可变带宽FRM滤波新结构

设计窄过渡带FIR滤波器的一种非常有效的方法是采用频率响应屏蔽技术(FRM).但是如果过渡带要求过窄,经典FRM滤波器各子滤波器的阶数会变得很高.据此,本文提出一种可变带宽镜像半带滤波FRM滤波新结构,通过增加两个镜像半带滤波器,将原型滤波器及其互补滤波器的镜像分别分成奇偶两部分,使得原型滤波器和屏蔽滤波器的设计更加灵活,并降低了滤波器的计算复杂度,达到了设计高效窄过渡带滤波器的目的.理论分析和实例均验证了该结构的有效性.     

A current-mode gain-control scheme with constant bandwidth andpropagation delay for a transimpedance preamplifier

This paper presents a current-mode gain-control scheme that significantly increases the input dynamic range of a wideband optoelectronic receiver without affecting its bandwidth or delay or deteriorating its noise properties. A current buffer with variable attenuation is placed between the photodetector and the transimpedance preamplifier. In this way, the input dynamic range of the receiver can be increased, or alternatively, the signal dynamics can be reduced, by over 20 dB. A BiCMOS test circuit designed for a pulsed time-of-flight laser rangefinder has a measured bandwidth of 170 MHz and an input dynamic range of ~80 dB. The delay varies only ±5 ps when the gain is varied by 24 dB (1:15)     

Optical preamplifier using optical modulation of amplified spontaneous emission in saturated semiconductor optical amplifier

This paper demonstrates a novel optical preamplifier using optical modulation of amplified spontaneous emission (ASE) emitted from a saturated semiconductor optical amplifier (SOA). Requirements on optical alignments and antireflection coating for SOAs can be relaxed and the elimination of an optical filter gives us a large tolerance of an input light wavelength in the proposed optical preamplifier. A small-signal gain of a fabricated preamplifier was over 13.5 dB for an input power of below -20 dBm. An optical gain bandwidth was over 60 nm. We measured the small-signal response of the optically modulated ASE. The 3 dB bandwidths at SOA bias currents of 200, 300, and 400 mA were 5.8, 12.6, and 16.5 GHz, respectively. We also investigated improvements in receiver sensitivities with the proposed optical preamplifier. Our calculation shows a possibility of 10 dB improvement in receiver sensitivities by using the optical preamplifier at 10 Gb/s. The measured receiver sensitivity was -22.7 dBm at 10 Gb/s with the optical preamplifier, which is corresponding to an improvement of 2.5 dB in the receiver sensitivity. Further improvements of the receiver sensitivity can be expected by optimizing the structure of SOAs for saturating ASE.     

High performance power-configurable preamplifier in a high-density parallel optical receiver

A power-configurable high performance preamplifier was implemented in standard 180-nm CMOS technology for 12 × 10 Gb/s high-density ultra-high speed parallel optical communication system. With critical limitations on power consumption, area and fabrication cost, the preamplifier achieves high performance, e.g. high bandwidth, high trans-impedance gain, low noise and high stability. A novel feed-forward common gate (FCG) stage is adopted to alleviate contradictions on trans-impedance gain and bandwidth by using a low headroom consuming approach to isolate a large input capacitance and using complex pole peaking techniques to substitute inductors to achieve bandwidth extension. A multi-supply power-configurable scheme was employed to avoid wasteful power caused by a pessimistic estimation of process-voltage-temperature (PVT) variation. Two representative samples provide a trans-impedance gain of 53.9 dBΩ, a 3-dB bandwidth of 6.8 GHz, a power dissipation of 6.26 mW without power-configuration and a trans-impedance gain of 52.1 dBΩ, a 3-dB bandwidth of 8.1 GHz, a power dissipation of 6.35 mW with power-configuration, respectively. The measured average input-referred noise-current spectral density is no more than 28 pA/Hz. The chip area is only 0.08 ? 0.08 mm².     

40 dB fibre optical preamplifier in 1064 nm laser Doppleranemometer

With a neodymium-doped fibre amplifier a small signal gain of 40 dB at 1064 nm has been achieved. Using the same amplifier as an optical preamplifier in a conventional 1064 nm laser Doppler anemometer (LDA), an improvement in the SNR of the LDA radiation and sensitivity enhancement in comparison to that for direct detection with a highly sensitive avalanche photodiode was obtained     

DCG窄带反射滤光片再现波长和带宽的控制方法

本文从DCG的成像特性出发 ,讨论了用DCG制作全息窄带反射滤光片时 ,干板制备、曝光记录、显影处理以及暗反应和后光化反应对全息滤光片的再现波长和反射带宽的影响 ,并给出了控制再现波长和带宽的方法。     

Variable bandwidth birefringent filter for stable femtosecondlasers

A design for a birefringent filter is described, which is suitable for tunable femtosecond lasers. Using a single plate, which has a steeply diving optic axis, two-octave tunability is attained with negligible deterioration of the stopband rejection. For a specific wavelength region, it means that the filter's bandwidth can be changed by a factor of four. Another characteristic of the design is that, for the same bandwidth, the proposed plate is five times thicker than a conventional plate in which the optic axis is parallel to the surface. Thus, etalon effects can be avoided. Tuning characteristics of color center lasers utilizing the new filter are also presented     

High-gain low-noise mid-infrared quantum cascade optical preamplifier for receiver

Optical preamplifier (OPA) in the mid-infrared can boost weak signals in systems such as lidars or optical wireless links to improve the receiver sensitivity. Quantum-cascade-based traveling-wave OPA with off-normal Bragg-grating (BG) coupled surface-emitting configuration have been developed with a net small-signal gain up to 13 dB over a spectral range /spl sim/70 nm around 4.7 /spl mu/m, limited by the wafer gain bandwidth, and the linear dynamic range was >20 dB. Amplified spontaneous emission (ASE) was measured and the spontaneous emission factor was determined N/sub sp//spl sim/1, indicating near quantum-limit noise behavior. Surface-emitting BG devices yielded diffraction-limited output beam, and provided simultaneous wavelength dispersion and ASE filtering. The OPA was coupled with a detector to form a receiver that is polarization-selective, has a net gain 8-13 dB with a corresponding optical filter bandwidth 25-50 GHz. These results suggest that BG-coupled OPA receivers can be useful for multispectral/wavelength-division-multiplexing systems in free space applications.     

Transimpedance optical preamplifier with a very low input resistance

A PIN photodiode-bipolar transistor transimpedance optical preamplifier with a very low input resistance is described that exhibits certain advantages over more conventional designs using common-emitter or common-collector input stages. The common-base input configuration enables optimum performance to be maintained with lower-cost photodiodes exhibiting a moderate capacitance of 2-7 pF.     

Inflection of shock response spectrum of filter bandwidth

目前利用冲击响应谱作为参考的冲击实验在国防事业、国家经济生活中得到广泛的应用,冲击响应谱也成为国防事业和经济生活中重要的参考标准,分析对冲击响应谱造成影响的因素,将有利于对冲击响应谱,规范,为更好实现冲击实验提供精确的参数设置。实验过程中为了得出冲击信号滤波带宽对冲击响应谱的影响,利用霍普金森杆产生高g值,窄带宽的冲击信号,再结合信号分析软件对得到的数据进行处理,得出滤波带宽影响冲击响应谱的等冲区的结论。     

滤波带宽对冲击响应谱的影响研究

目前利用冲击响应谱作为参考的冲击实验在国防事业、国家经济生活中得到广泛的应用,冲击响应谱也成为国防事业和经济生活中重要的参考标准,分析对冲击响应谱造成影响的因素,将有利于对冲击响应谱规范,为更好实现冲击实验提供精确的参数设置。实验过程中为了得出冲击信号滤波带宽对冲击响应谱的影响,利用霍普金森杆产生高g值,窄带宽的冲击信号,再结合信号分析软件对得到的数据进行处理,得出滤波带宽影响冲击响应谱的等冲区的结论。