7.1 GHz bandwidth monolithically integratedIn0.53Ga0.47As/In0.52Al0.48As PIN-HBT transimpedance photoreceiver

A monolithically integrated photoreceiver using an InAlAs/InGaAs HBT-based transimpedance amplifier has been fabricated and characterized. The p-i-n photodiode is implemented using the base-collector junction of the HBT. The 5 μm×5 μm emitter area transistors have self-aligned base metal and non-alloyed Ti/Pt/Au contacts. Discrete transistors demonstrated f_T and f_max of 54 GHz and 51 GHz, respectively. The amplifier demonstrated a -3 dB transimpedance bandwidth of 10 GHz and a gain of 40 dBΩ. The integrated photoreceiver with a 10 μm×10 μm p-i-n photodiode showed a -3 dB bandwidth of 7.1 GHz     

A design technique for a 60 GHz-bandwidth distributed basebandamplifier IC module

A DC-60 GHz, 9 dB distributed amplifier IC module is fabricated with 0.15 μm InAlAs-InGaAs low-noise HEMTs with 155 GHz f_T and 234 GHz f_max. The device is mounted in a metal package with 1.8 mm coaxial cable signal interfaces. The package is specially designed using three-dimensional electromagnetic field analyses, resulting in very flat frequency characteristics of the module within 1.5 dB gain ripples over the entire bandwidth. A multichip module loaded with two amplifier ICs in cascade is also fabricated, and operates at a 17.5 dB gain from 60 kHz to 48 GHz. The 1 dB gain compression output power is about 5 dBm for both modules. The noise figure of the single-chip module is approximately 4 dB over a 10-40 GHz frequency range     

High gain operational amplifier implemented in 0.5 μm GaAs E/DHEMT technology

A high voltage gain operational amplifier implemented in 0.5 μm GaAs E/D HEMT technology is presented. The amplifier principally consists of a differential input stage and a high gain cascode stage which was developed by Toumazou and Haigh (1990). On-wafer measurement verifies that the amplifier achieves an open-loop voltage gain of 73 dB and a unity-gain bandwidth of 1.78 GHz     

2-Gbit/s signal amplification at λ=1.53 μm in anerbium-doped single-mode fiber amplifier

The gain, saturation power, and noise of an erbium-doped single-mode traveling-wave fiber amplifier operating at a wavelength λ=1.53 μm are characterized. In continuous-wave (CW) measurements amplification at 2 Gbit/s was demonstrated with up to 17-dB gain for 1×10^-9 bit error rate at 1.531 μm and a 3-dB full bandwidth of 14 nm. From the determination of the fiber-amplifier's output signal-to-noise ratio versus input signal power during data transmission, it was concluded that, with signal levels used here, signal-spontaneous beat noise limited the receiver sensitivity improvement. With the fiber amplifier acting as an optical preamplifier of the receiver, the best sensitivity was -30 dBm, obtained after installing a polarizer at the fiber amplifier output to reject half of the applied spontaneous emission power. This sensitivity was 6 dB better than without the fiber amplifier, proving that the fiber amplifier can be used as a preamplifier     

Multipass diode-pumped Nd:YAG optical amplifiers at 1.06 μm and1.32 μm

We have built two versions of a diode-pumped Nd:YAG amplifier using a compact multipass confocal geometry with a fiber-coupled input. This confocal geometry provided efficient power and high gain in a volume of approximately 100 cm³. When pumped with a commercially mature 2 W 809 nm laser diode, the 1.06 μm version produced 460 mW and a small signal gain of 51 dB. The 1.32 μm version produced 170 mW and a small signal gain of 29 dB. Such an efficient amplifier, especially at 1.32 μm would be useful as a power booster in fiber optic telecommunications     

A power-efficient, low-distortion variable gain amplifierconsisting of coupled differential pairs

A variable gain amplifier incorporating a plurality of coupled differential pairs has been designed in a bipolar technology. By applying variable offset voltages to these differential pairs, the overall gain of the system can be varied. The linear input region is inversely proportional to gain, making the amplifier very well suited for automatic gain control circuits. Furthermore, the gain of the proposed amplifier is 0-25 dB, the signal bandwidth is 35 MHz, and the output IP3 is 24-30 dBm. It operates from a 5 V power supply and dissipates 40 mW. The active chip area is 0.15 mm² in a 1 μm bipolar technology     

Er3+-doped fiber amplifier pumped by 0.98 μm laserdiodes

The performance of an Er³⁺-doped fiber amplifier pumped by 0.98 μm InGaAs laser diodes (LDs) is reported. By using a fiber with low Er³⁺ content and optimizing the fiber length, a maximum signal gain of 37.8 dB at 30-mW pump power was realized at a signal wavelength of 1.536 μm. A maximum gain coefficient of 1.9 dB/mW at 14 mW pump power was achieved. It was found that the fiber amplifier pumped by the 0.98-μm LDs is twice as efficient as that pumped by 1.48-μm LDs, from the viewpoint of both required fiber length and the attained gain     

1.55-μm polarization-insensitive optical amplifier withstrain-balanced superlattice active layer

A polarization insensitive (sensitivity <1 dB) GaInAs-GaInAsP semiconductor optical amplifier has been realized at 1.55 μm. The active layer consists of a strain-balanced superlattice structure. Gain polarization insensitivity on a large bandwidth (60 nm) together with a 22.5-dB signal gain and a 11-dBm polarization-insensitive saturation output power are obtained     

1.4-μm-band gain characteristics of a Tm-Ho-doped ZBLYAN fiberamplifier pumped in the 0.8-μm band

The gain characteristics of a 1.4-μm-band thulium-holmium-doped ZBLYAN fiber amplifier are described. Signal gain is obtained over the whole 1.4-μm band for a pump power level of 73.5 mW. A maximum signal gain of 18 dB is achieved at a signal wavelength of 6.46 μm for a pump power of 150 mW at 0.79 μm. The noise figure is 5.6 dB in the signal wavelength region from 1.45-1.50 μm. From a comparison of the gain characteristics of thulium-holmium-doped ZBLYAN fibers and thulium-doped ZBLYAN fibers, it is proved that holmium ions play an effective role in increasing the gain and widening the gain spectrum     

Vertical-cavity amplifying modulator at 1.3 μm

The modulation/switching properties of a vertical-cavity semiconductor optical amplifier operating at 1.3 μm wavelength are investigated. The device was optically pumped and operated in reflection mode. A 150-mV (100 mA) modulation of the drive to the pump source produced a 7-dB modulation of the pump power, which produced a 35-dB modulation in the output signal. The maximum extinction ratio was 35 dB, and limited by device heating. Frequency response measurements revealed a modulation bandwidth of 1.8 GHz when the amplifier was saturated. This enabled 2.5-Gb/s modulation of a -10 dBm input signal with 5.5-dB fiber-to-fiber gain     

High-drive CMOS current amplifier

A high-performance current amplifier is proposed which is based on a folded-cascode transresistance amplifier and a low-distortion class AB current output stage. The loop gain of the transresistance amplifier exhibits a gain bandwidth product of 10 MHz and a DC gain as high as 100 dB which allows accurate closed-loop operations to be achieved. Despite the intrinsic low-linearity performance of current amplifiers with respect to their voltage amplifier counterpart, the proposed circuit provides an output current of 7 mA with a total harmonic distortion (THD) better than -55 dB while requiring only 200 μA of quiescent current for the output transistors. The circuit was fabricated in a 1.2 μm CMOS process, uses a 5 V power supply, and dissipates 4 mW     

Broadband amplification in CMOS technology using cascadedsingle-stage distributed amplifier

Feasibility of the cascaded single-stage distributed amplifier (CSDA) for ultra broadband amplification in complementary metal-oxide-semiconductor (CMOS) technology is investigated. A number of unique benefits gained from the CMOS CSDA over the conventional CMOS distributed amplifier structure are highlighted along with bandwidth analysis and helpful consideration. Simulated in the standard digital 0.35 μm CMOS process with realistic parasitic models, a prototype design of a four-stage CMOS CSDA provides 21 dB power gain at 5 GHz bandwidth, better than -10 dB input/output return loss and dissipates < 132 mW     

Monolithically integrated multichannel SiGe/Si p-i-n-HBTphotoreceiver arrays

A low-power, short-wavelength eight-channel monolithically integrated photoreceiver array, based on SiGe/Si heterojunction bipolar transistors, is demonstrated. The photoreceiver consists of a photodiode, three-stage transimpedance amplifier, and passive elements for feedback, biasing and impedance matching. The photodiode and transistors are grown by molecular beam epitaxy in a single step. The p-i-n photodiode exhibits a responsivity of 0.3A/W and a bandwidth of 0.8 GHz at λ=0.88 μm. The three-stage transimpedance amplifier demonstrates a transimpedance gain of 43 dBΩ and a -3 dB bandwidth of 5.5 GHz. A single channel monolithically integrated photoreceiver consumes a power of 6 mW and demonstrates an optical bandwidth of 0.8 GHz. Eight-channel photoreceiver arrays are designed for massively parallel applications where low power dissipation and low crosstalk are required. The array is on a 250-μm pitch and can be easily scaled to much higher density. Large signal operation up to 1 Gb/s is achieved with crosstalk less than -26 dB. A scheme for time-to-space division multiplexing is proposed and demonstrated with the photoreceiver array     

Neodymium-doped fibre amplifier at 1.064 μm

For the first time, a fibre amplifier with a small signal gain of more than 30 dB at 1.064 μm has been realised. The amplifier employs an Nd-Al codoped fibre and a 0.808 μm pumping laser diode which offers 50 mW incident pump power     

Atmospheric pressure MOVPE growth of high performance polarisationinsensitive strain compensated MQW InGaAsP/InGaAs optical amplifier

The authors report a structure for a polarisation insensitive amplifier at 1.55 μm wavelength using 16 compensated strain InGaAsP/InGaAs quantum wells. A high gain of 27 dB for TE and TM modes has been obtained. Polarisation sensitivity less than 1 dB over 85 nm bandwidth has been measured. These results are among the best reported     

High gain wideband amplifier IC using 0.7 μm GaAs MESFETtechnology

A high gain wideband differential amplifier with a new circuit configuration is proposed and monolithically integrated by using 0.7 μm-gate GaAs MESFET IC technology. The fabricated IC exhibited gain of 16.7 dB and bandwidth of 3.2 GHz. A gain twice that of a conventional differential GaAs-MESFET amplifier was achieved with small bandwidth degradation     

10Gb/s GaAs PHEMT高增益光接收机前置放大器

基于南京电子器件研究所0.5μm GaAs PHEMT工艺,研制了一种高增益级联式光接收机前置放大器.作为前级的跨阻抗放大器的-3dB带宽为10GHz,小信号增益为9dB;作为后级的分布式放大器的-3dB带宽接近20GHz,小信号增益为12dB;级联前置放大器小信号增益达21.3dB,跨阻增益为55.3dBΩ,在输入10Gb/s非归零伪随机二进制序列下,放大器输出眼图清晰、对称、信噪比优于跨阻放大器,分布放大器不能校正的输入波形失真也得到显著改善.     

A 50 dB variable gain amplifier using parasitic bipolar transistorsin CMOS

A variable-gain amplifier (VGA) with a gain range of 50 dB has been implemented in a standard 3 μm CMOS process using parasitic lateral and vertical bipolar transistors to form the core of the circuit. The bipolar transistors had been characterized extensively. The VGA has a bandwidth larger than 3 MHz over the whole gain range and operates on a single 5 V power supply. The active area is about 0.8×0.9 mm²     

Dy-doped chlorides as gain media for 1.3 μm telecommunicationsamplifiers

We propose that Dy³⁺-doped chloride crystals be considered as candidates for amplification of the 1.3 μm signal used by the telecommunications network. While several of these types of crystals can provide gain at the specified operating wavelength of 1.31 μm, and furthermore offer adequate bandwidth, we have focused our attention on LaCl₃:Dy as an illustrative case to explore in greater depth. Spectroscopic measurements were made on un-oriented samples of this material; excited-state lifetimes and LaCl₃:Dy³⁺ Judd-Ofelt parameters are reported. Wavelength-resolved absorption and emission cross sections are presented for the 1.3 μm W&rlhar2;Z band. Pump-probe measurements (using 0.92 μm and 1.32 μm, respectively) prove that the observed gain properties of LaCl₃:Dy are consistent with those predicted on the basis of the spectroscopic cross sections. The Dy:chloride gain media appear to have fundamental optical characteristics amenable to superior 1.3 μm telecom amplifier performance, although many fabrication issues would have to be addressed to produce a practical amplifier     

1.3-μm Pr-doped In-Ga-based fluoride fiber amplifiers pumped bygrating-fiber-pigtailed 0.98-μm-band laser diodes with a detunedwavelength of 1 μm

At most efficient pump wavelength, a praseodymium-doped In-Ga-based fluoride fiber is directly pumped by four 0.98-μm-band laser diodes. These lasing wavelengths are detuned from 0.98 to 1 μm by external selective optical feedback from fiber grating reflectors. Maximum signal output power of +13.5 dBm is obtained at 1.296 μm. Four-wavelength multiplexed signals at 1.296-1.311 μm are amplified with a deviation of gain less than 1.9 dB. By using the amplifier as a power booster, data of 2.5 Gb/s is successfully transmitted more than 100 km