0.98- mu m strained quantum well lasers for coupling high optical power into single-mode fiber

An investigation of epitaxial-layer structures has yielded narrow ridge waveguide structure lasers capable of coupling high optical power into single-mode fiber (SMF). An optical power of well over 60 mW in SMF was obtained for a 2- mu m-wide ridge waveguide laser with a guided separate-confinement-heterostructure (SCH) epitaxial structure. Calculated results indicate that the stringent limit imposed on 0.98- mu m wavelength detuning is relaxed for such high optical power coupled into a SMF. The 0.98- mu m strained-quantum-well lasers thus show considerable promise as a practical low-noise pumping source for Er-doped optical-fiber amplifiers.<>     

Low-threshold synchronously pumped all-fiber ring Raman laser

Experimental results on a synchronously pumped, all single-mode fiber Raman laser with a low threshold of 740 mW are reported. Suppression of gain fluctuations due to pump phase noise has been achieved by implementing a fiber coupler of high multiplexing effect. Multistokes generation of low-noise optical pulse trains atlambda = 1.12 mum andlambda = 1.18 mum has also been obtained with a subwatt pump threshold.     

A 1.25-inch 60-frames/s 8.3-M-pixel digital-output CMOS image sensor

The ultrahigh-definition television (UDTV) camera system requires an image sensor having four times higher resolution and two times higher frame rate than the conventional HDTV systems. Also, an image sensor with a small optical format and low power consumption is required for practical UDTV camera systems. To respond to these requirements, we have developed an 8.3-M-pixel digital-output CMOS active pixel sensor (APS) for the UDTV application. It features an optical format of 1.25inch, low power consumption of less than 600 mW at dark, while reproducing a low-noise, 60-frames/s progressive scan image. The image sensor is equipped with 1920 on-chip 10-bit analog-to-digital converters and outputs digital data stream through 16 parallel output ports. Design considerations to reproduce a low-noise, high-resolution image at high frame rate of 60 fps are described. Implementation and experimental results of the 8.3-M-pixel CMOS APS are presented.     

High-Speed Optical Receivers With Integrated Photodiode in 130 nm CMOS

The design and measurement of two optical receivers with integrated photodiode in 130 nm CMOS is presented. The low bandwidth, which is typical for photodiodes in CMOS technologies, is circumvented by a differential photodiode topology on the one hand and by including an optimized equalizer in the receiver chain on the other hand. The low responsivity of a CMOS photodiode is compensated by a very low-noise design for the differential TIA. The disadvantage of such a low-noise design is its high power consumption. Therefore, a design strategy is presented where part of the circuit is biased in weak inversion. Doing so, the power consumption is decreased from 138 mW for the standard design to only 74.16 mW. Both designs are measured optically with 850 nm modulated light and are able to operate at 4.5 Gbit/s with a BER lower than 10^-12. The sensitivities for this BER and speed are - 3.8 dBm and -3.4 dBm respectively. The receivers even work up to 5 Gbit/s for BER values around 10^-9.     

Low-noise 650-nm-band AlGaInP visible laser diodes with a highlydoped saturable absorbing layer

Stable self-sustained pulsating and low-noise 650-nm-band AlGaInP visible laser diodes were demonstrated by adopting a novel structure, which has a highly doped saturable absorbing (SA) layer. Short carrier lifetime, which is indispensable for self-pulsation, was realized by applying high doping concentration to the p-type SA layer. 500-μm-long devices with 51%/51% coated facets were fabricated, resulting in the threshold current of 75 mA at 20°C. The temporal output power was measured at the average output power of 5 mW and the stable self-pulsation was observed up to an ambient temperature of 60°C. Therefore, the relative intensity noise (RIN) was kept about -140 dB/Hz in temperature ranging from 20°C to 60°C. Since the refractive index difference could be kept large and the optical mode could be confined effectively, the astigmatism in this work was below 3 μm at 5 mW against dc injection current. The lasers operated over 1350 h under the average output power of 5 mW at 60°C     

Dispersion-compensator incorporated optical fiber amplifier

An optical fiber amplifier incorporating a dispersion compensator such as a dispersion compensating fiber (DCF) is proposed and examined theoretically and experimentally. The new amplifier requires only a single pump laser. In the experiment a 0.98-μm laser diode was used and the pump power was 50 mW. By utilizing remnant pump power, the amplifier can halve the loss effect of the compensator and double the apparent figure of merit of the DCF (ps/nm/dB). The noise figure of the new amplifier is not affected by inserting the DCP. A low-noise figure of 5 dB was obtained over a wide input-power range of -40 to -10 dBm     

Design techniques for subcarrier multiplexed broadcast opticalnetworks

Design techniques which enable the performance of subcarrier multiplexed FM broadcast optical networks to be optimized at the planning stage are described. At the transmitter node, criteria for maximizing the subscriber carrier-to-noise ratio (CNR) are presented. At the subscriber node, it is shown that under the majority of circumstances, the optimum direct detection receiver consists of a low-noise III-V avalanche photodiode and high-impedance front-end preamplifier. Sensitivities approaching -40 dB (1 mW) for 16.5 dB CNR in 36 MHz subscriber bandwidth are predicted for a 60-channel system. Preliminary experimental tests on an optical-feedback subcarrier receiver showed -34 dB (1 mW) sensitivity at 1.55 μm from 16.5 dB CNR in a 36 MHz bandwidth centered on 1.2 GHz with a 12% modulation index single-channel FM test signal     

A SiGe BiCMOS burst-mode 155-Mb/s receiver for PON

In this paper, we present an integrated 155-Mb/s burst-mode receiver (BMR) for passive optical network (PON) applications. The chip has been designed to receive optical signals over a wide dynamic range (-30 to -8 dBm) and temperature range (-40°C to +85°C). The chip was implemented using a 0.8-μm 35-GHz SiGe BiCMOS technology and occupies an area of 4.3×4.9 mm² with a power consumption of 500 mW from a supply voltage of 5 V (3.3 V for the digital PECL output). In the receiver analog front end, we used a low-noise wide-band transimpedance amplifier followed by a nonlinear gain stage to cover a wide signal range without changing the transimpedance gain. The circuit dynamically adjusts the receiver threshold voltage through a feedback loop, thus optimizing the pulsewidth distortion and canceling the optical as well as the electrical offset voltages     

A family of differential NMOS analog circuits for a PCM codec filter chip

A new NMOS PCM codec filter uses low-noise fully differential circuits to achieve supply rejection of 36 dB and idle channel noise of 6 dB/SUB rnc0/. The die size is 24 mm/SUP 2/ and the active standby power is 150 mW/5 mW.     

10 GHz bandwidth 20 dB gain low-noise direct-coupled amplifier ICs using Au/WSiN GaAs MESFET

A low-noise direct-coupled amplifier IC with a bandwidth of 10 GHz was developed using a 0.4 mu m gate-length Au/WSiN GaAs MESFET technology. The amplifier achieved a high gain of 20 dB and a minimum noise figure of 3.2 dB with a power consumption of 365 mW.<>     

Low-noise tape preamplifier with new self-biasing architecture

A low-noise ground-compatible preamplifier for audio signal processing is presented. It amplifies the audio signal coming from a magnetic head producing a total input-referred voltage noise less than 300-nV r.m.s. CCIR/ARM weighted in operative conditions thanks to a low-noise bipolar amplifier, while auto-reverse, metal/normal, and mute facilities are available on chip using low-noise offset-free analog CMOS switches. Total harmonic distortion was less than 0.004% in full dynamic range. This performance was obtained using a nonconventional self-biasing ground-compatible preamplifier architecture, particularly intended for single supply applications, that does not require any external components and auxiliary voltage reference. The preamplifier occupies 1.5 mm/sup 2/ and dissipates 38 mW with a 10-V power supply. A measured power supply rejection of about 120 dB at 1 kHz was obtained using internal regulated voltage supply.<>     

Alumina microstrip GaAs f.e.t. 11 GHz oscillator

A small, lightweight 11 GHz f.e.t. oscillator has been developed. An output power of 10 mW with an efficiency of 10% was easily produced using a GaAs f.e.t. designed for small-signal amplifier applications. Its low power consumption makes it a suitable low-noise source for integrated-receiver applications.     

A 65-nm low-noise low-costΣ△modulator for audio applications

正This paper introduces a low-noise low-costΣA modulator for digital audio analog-to-digital conversion. By adopting a low-noise large-output swing operation amplifier,not only is the flicker noise greatly inhibited,but also the power consumption is reduced.Also the area cost is relatively small.The modulator was implemented in a SMIC standard 65-nm CMOS process.Measurement results show it can achieve 96 dB peak signal-to-noise plus distortion ratio(SNDR) and 105 dB dynamic range(DR) over the 22.05-kHz audio band and occupies 0.16 mm~2. The power consumption of the proposed modulator is 4.9 mW from a 2.5 V power supply,which is suitable for high-performance,low-cost audio codec applications.     

Upconversion pumped thulium-doped fluoride fiber amplifier andlaser operating at 1.47 μm

A 1.064-μm band upconversion pumped Tm³⁺-doped fluoride fiber amplifier and a laser both operating at 1.47 μm are investigated in detail. The two devices are based on the ³F ₄→³H₄ transition in a trivalent thulium ion, which is a self-terminating system. When pumped at 1.064 μm, the amplifier has a gain of over 10 dB from 1.44 to 1.51 μm and a low-noise characteristic. Also, the fiber laser generates a high-output power of over 100 mW with a slope efficiency of 59% at around 1.47 μm. These levels of performance will be important for optical communication systems     

A 1.9 GHz low-voltage silicon bipolar receiver front-end forwireless personal communications systems

A 1.9 GHz wireless receiver front-end (low-noise preamplifier and mixer) is described that incorporates monolithic microstrip transformers for significant improvements in performance compared to silicon broadband designs. Reactive feedback and coupling elements are used in place of resistors to lower the front-end noise figure through the reduction of resistor thermal noise, and this also allows both circuits to operate at supply voltages below 2 V. These circuits have been fabricated in a production 0.8 μm BiCMOS process that has a peak npn transistor transit frequency (f_T) of 11 GHz. At a supply voltage of 1.9 V, the measured mixer input third-order intercept point is +2.3 dBm with a 10.9 dB single-sideband noise figure. Power dissipated by the mixer is less than 5 mW. The low-noise amplifier input intercept is -3 dBm with a 2.8 dB noise figure and 9.5 dB gain. Power dissipation of the preamplifier is less than 4 mW, again from a 1.9 V supply     

星间激光通信发射终端耦合单元的研究

针对星间光通信系统的要求,采用一种新型的半导体激光耦合方案,用前后正交的非球面柱面透镜准直半导体激光束,再经渐变折射率(graduated refractive index,GR IN)自聚焦透镜聚焦,把光束耦合入单模光纤。就此耦合单元,对耦合效率随半导体激光器的位置偏离及角度偏移进行了研究,在光纤尾纤处测得了输出功率随驱动电流的变化关系,单模运行的半导体激光二极管经耦合后的出纤功率可以达到80mW。结果表明,耦合效率随位置偏离及角度偏移的变化灵敏度都不高,这可以满足星间光通信的要求。     

0.6V CMOS低噪声放大器的设计与优化*

采用SMIC 0.18 μm CMOS工艺设计了一个低电压低功耗的低噪声放大器(Locked Nucleic Acid,LNA).分析了在低电压条件下LNA的线性度提高及噪声优化技术.使用Cadence SpectreRF仿真表明,在2.4 GHz的工作频率下,功率增益为19.65 dB,输入回波损耗S11为-12.18 dB,噪声系数NF为1.2 dB,1 dB压缩点为-17.99 dBm,在0.6V的供电电压下,电路的静态功耗为2.7 mW,表明所设计的LNA在低电压低功耗的条件下具有良好的综合性能.     

基于扫描激光器和光放大的100 km光纤布拉格光栅传感系统

提出了对基于扫描激光器的光纤布拉格光栅(FBG)传感系统进行掺铒光纤(EDF)/双波拉曼混合放大的方法,大幅度提高了该光纤布拉格光栅传感系统的传输距离。该方法以高功率扫描激光器作为光源,采用双波长拉曼放大的方法对信号进行低噪声双向放大,再利用系统中间的两段掺铒光纤,将剩余的拉曼抽运功率用来产生自发辐射光和放大传感信号,使得整个系统能在超长的传感距离上获得良好的信噪比(SNR)。实验表明使用一台扫描激光传感分析仪、一只170mW的拉曼抽运和一只2W的拉曼抽运,可以使传感距离达到100km以上,并且传感系统的光纤布拉格光栅反射信号均能获得超过7dB的良好信噪比,从而实现在超长距离上的光纤布拉格光栅传感。     

Low-noise, low-power monolithically integrated active 20 GHz mixerin SiGe technology

A monolithically integrated active broadband mixer for wireless communications in a 0.5 μm 80 GHz f_T SiGe bipolar technology is presented. The circuit is optimised for low-noise and low-power consumption and operates up to 20 GHz with a conversion gain >10 dB consuming only 9 mW from a single 4.5 V supply     

13 GHz 4.67 dB NF CMOS low-noise amplifier

The design and measured results of a fully-integrated 13 GHz CMOS low-noise amplifier (LNA) are presented. Effects of substrate resistances on LNA performance are discussed. The LNA has 4.67 dB noise figure and +8.5 dBm of input-referred third-order intercept point (IIP3) with a power consumption of 9.72 mW.