0-40 GHz GaAs MESFET distributed baseband amplifier ICs forhigh-speed optical transmission

We describe distributed amplifiers built using advanced circuit design techniques to improve gain and noise performance at low frequencies. Using these techniques we have developed an amplifier IC with a 0-36 GHz bandwidth and a noise figure of 4 dB at low frequencies. This frequency range starting from 0 Hz makes it possible to use the IC as a baseband amplifier for SDH optical transmission systems and this noise figure is about 1 dB better than conventional distributed amplifiers. We also present another amplifier IC built using our loss compensation technique to improve high-frequency performance of the amplifier. This IC has a 0-44-GHz bandwidth, which is the widest among all reported GaAs MESFET baseband amplifiers     

Over-10-Gb/s IC's for future lightwave communications

This paper reviews research and development in NTT Laboratories on IC's faster than 10 Gb/s for future optical communication systems. Novel design and circuit techniques achieve such high-speed IC's and stable operation even in packages and modules. High-bit-rate operation of 10 Gb/s (10-GHz equalizing amplifier circuit, a 10-GHz clock recovery circuit, 10-Gb/s decision circuits, and 10-Gb/s multiplexers and demultiplexers) is obtained. 20-Gb/s operation is also achieved for some IC's. Future improvements using advanced device and circuit technologies are discussed, and bit rates over 40 Gb/s are predicted     

InGaAs/InP DHBT technology and design methodology for over 40 Gb/soptical communication circuits

High-performance technologies and adequate design methodologies are required to address the needs of very high-speed ICs (VHSICs) for over 40 Gb/s optical communications. We describe improvements we have introduced in our InP DHBT technology, and how our design methodology has evolved, we show how it results in improved circuit designs, and present some recent results, with some considerations on measurement limitations     

A 54-GHz distributed amplifier with 6-V/sub PP/ output for a 40-Gb/s LiNbO/sub 3/ modulator driver

We have developed a distributed amplifier for a LiNbO/sub 3/ modulator driver using double-doped AlGaAs-InGaAs-AlGaAs pseudomorphic high electron mobility transistors (p-HEMTs). By using a stabilization and negative resistance control technique with source inductance and grounded coplanar waveguided lines, we obtained a gain of 15 dB, a bandwidth of 54 GHz, and 6-V/sub PP/ output. These results indicate that our circuit is a leading candidate for use as a LiNbO/sub 3/ modulator driver in 40-Gb/s fiber-optic communication systems.     

Design of an opto-electronic modulator driver amplifier for 40-Gb/s data rate systems

This paper describes the design and performance of a broad-band driver amplifier for 40-Gb/s noreturn-to-zero system applications. The function of the amplifier is to raise the output from a multiplexer (nominally 0.4 V peak to peak) to a level of /spl sim/5 Vp-p, which is suitable to drive a GaAs-based Mach-Zehnder optoelectronic modulator. The amplifier module contains two GaAs pseudomorphic high-electron mobility transistor traveling-wave MMICs fabricated on a 0.2-/spl mu/m gate process. The design issues relating to the specific requirements of a modulator driver amplifier and the techniques to resolve them are described.     

Highly reliable uni-travelling-carrier photodiodes for 40 Gbit/soptical transmission systems

The reliability of InP/InGaAs uni-travelling-carrier photodiodes has been studied. A failure rate of 42 FIT at 25°C was estimated from long-term bias-temperature stress tests. Stable operations for over 2000 h were also confirmed under higher-power optical input conditions     

InP-HBT chip-set for 40-Gb/s fiber optical communication systemsoperational at 3 V

A chip set for a 40 Gb/s fiber optical communication system has been designed and fabricated. On-wafer measurements have been performed to verify circuit operations. As far as available measurement capabilities show, all circuits are functionally fulfilling specifications for 10 Gb/s operation at less than or equal to 3 V supply voltage. During the design phase especially the influence of interconnects on signal integrity was investigated and the results were implemented for automatic extraction. All the circuits were operational after the first processing round. No redesign was necessary     

Statistical measurements of BER fluctuations due to PMD in 10-Gb/soptical transmissions

Polarization-mode dispersion induces signal fading and fluctuating power penalties in optical systems. The intrinsic uncertainty of the bit error rate (BER) measurements combined to the time needed to perform power adjustments for a power penalty measurement can completely distort the statistics of the as-measured power penalties. We show that measuring the BER statistics and using the receiver sensitivity power dependence gives a better measurement of the power penalty statistics. The influence of the statistics of error detection in the measurements must be considered in order to define the correct measuring time for each situation     

A 3-V fully differential distributed limiting driver for 40-Gb/s optical transmission systems

A fully differential 40-Gb/s electro-absorption modulator driver is presented. Based on a distributed limiting architecture, the circuit can supply up to 3.0-V/sub pp/ (peak-to-peak) per side in a 50-/spl Omega/ load at data rates as high as 44 Gb/s. Both the input and the output are internally matched to 50 /spl Omega/ and exhibit return loss of better than 10 dB up to 50 GHz. Additional features of the driver include the use of a single -5.2-V supply, output swing control (1.7-3.0-V/sub pp/ per side), dc output offset control (-0.15 V to -1.1 V), and pulsewidth control (30% to 66%). The driver architecture was optimized based on a comprehensive analytical derivation of the frequency response of cascaded source-coupled field-effect transistor logic blocks using both single and double source-follower topologies.     

Comparison of EDFA and bidirectionally pumped Raman amplifier in a40-Gb/s RZ transmission system

We numerically compare the performance of a bidirectionally pumped Raman and an erbium-doped fiber amplifier (EDFA) system in a 40-Gb/s dispersion-managed return-to-zero (RZ) transmission. The Raman amplifier system shows a substantially higher Q-value compared to that of the EDFA     

High-gain transimpedance amplifier in InP-based HBT technology forthe receiver in 40-Gb/s optical-fiber TDM links

A monolithic integrated transimpedance amplifier for the receiver in a 40-Gb/s optical-fiber TDM system has been fabricated in an InP-based HBT technology. Despite its high gain (transimpedance of 2 kΩ in the limiting mode, 10 kΩ in the linear mode) the complete amplifier was realized on a single chip. Clear output eye diagrams were measured up to 43 Gb/s under realistic driving conditions. The voltage swing of 0.6 V_pp at the differential 50 Ω output does not change within the demanded input dynamic range of 6 dB. At the upper input current level even 48 Gb/s were achieved. The power consumption is approximately 600 mW at a single supply voltage of -5.5 V     

40-Gb/s tandem electroabsorption modulator

In this letter, we have developed a tandem electroabsorption modulator with an integrated semiconductor optical amplifier that is capable of both nonreturn-to-zero and return-to-zero (RZ) data transmission at 40 Gb/s. The tandem modulator consists of a broad-band data encoder and a narrow-band pulse carver. The pulse carver is able to produce 5-ps pulses with more than 20 dB of extinction. The on-chip semiconductor optical amplifier provides up to 8.5 dB of fiber-to-fiber gain and enables the modulator to be operated with zero insertion loss. Devices have been realized with greater than 40-GHz bandwidth, and 13-dB dynamic extinction for a 2.5-V swing. For optimized designs bandwidths of nearly 60 GHz: have been realized. Using these devices penalty free RZ data transmission over a 100-kin dispersion compensated fiber link has been demonstrated with a received power sensitivity of -29 dBm     

An experiment of automatic PMD compensation in 40-Gb/s RZ optical communication system

An experiment of adaptive polarization mode dispersion (PMD) compensation for 40-Gb/s return-to-zero (RZ) optical communication system is reported. In the experiment, degree of polarization (DOP) is used as feedback signal and particle swarm optimization (PSO) method is adopted as logic control algorithm.The compensation time is about 200 ms, the compensated differential group delay (DGD) is up to 30 ps,and bit error rate (BER) of 10-9 is reached when PMD compensation is employed.     

A Si BiCMOS transimpedance amplifier for 10-Gb/s SONET receiver

A transimpedance amplifier packaged with an InP p-i-n photodiode has been demonstrated for 10-Gb/s SONET receiver. The shunt feedback transimpedance amplifier is fabricated in 0.25-μm modular Si BiCMOS technology. The transimpedance of 55 dBΩ is achieved at a bandwidth of 9 GHz by applying shunt peaking and filter termination at the input. The optical sensitivity of -17 dBm was measured at 10 Gb/s for a bit-error rate of 10^-12     

Semiconductor light sources for 40-Gb/s transmission systems

The status and prospects of semiconductor light sources for 40-Gb/s transmission systems are reviewed in regard to the following three topics: direct modulation, external modulation, and pulse sources for return-to-zero format. Included are discussions on direct modulation of a 1.3-/spl mu/m distributed feedback laser for 40-Gb/s very-short-reach optical links, progress made in developing external modulators based on electroabsorption of multiple quantum wells, and mode-locked lasers for carrier-suppressed return-to-zero modulation format.     

An auto-gain control transimpedance amplifier with low noise andwide input dynamic range for 10-Gb/s optical communication systems

This paper describes a 10-Gb/s transimpedance amplifier (TIA), fabricated in a 0.1-μm-p-HEMT technology. To improve the optical overload characteristics, an automatic gain control (AGC) circuit is included. The measured results show excellent performance, transimpedance of 63.3 dBΩ (1.46 kΩ), bandwidth of 8.0 GHz, and equivalent input noise current density of 6.5 pA/rtHz. When the bit error rate is 10^-9, the minimum sensitivity and the optical overload are -21.2 dBm, +4.3 dBm, respectively, using a 0.8 A/W pin photodiode (PD). The power dissipation is about 0.5 W from a single -5-V supply. The die area is 1.3×1.6 mm²     

40-Gb/s ICs for future lightwave communications systems

This paper describes the device, circuit design, and packaging technologies applicable to 40-Gb/s-class future lightwave communications systems. A 0.1-μm gate InAlAs-InGaAs high electron mobility transistors (HEMTs) with InP recess etch stopper was adopted mainly for IC fabrication. Fabricated ICs demonstrate excellent data-multiplexing, demultiplexing, and amplifying operation at 10 Gb/s     

Numerical comparison between distributed and discrete amplificationin a point-to-point 40-Gb/s 40-WDM-Based transmission system with threedifferent modulation formats

We describe a detailed numerical investigation on the relative merits of gain flattened distributed Raman amplification (DRA) and discrete gain flattened amplifiers. We simulate a system with forty 40-Gb/s channels spaced at 100 GHz and compare the performance of three different modulation formats nonreturn-to-zero (NRZ), return-to-zero (RZ) and carrier-suppressed RZ (CS-RZ). Three types of amplifiers, multifrequency backward- and forward-pumped DRAs, and an idealized discrete gain flattened amplifier are examined for various signal powers and transmission distances. For the backward-pumped DRA, we also describe calculated tolerance limits imposed by incomplete dispersion slope compensation and polarization mode dispersion (PMD) level     

1.25-Gb/s regulated cascode CMOS transimpedance amplifier for Gigabit Ethernet applications

A transimpedance amplifier (TIA) has been realized in a 0.6-/spl mu/m digital CMOS technology for Gigabit Ethernet applications. The amplifier exploits the regulated cascode (RGC) configuration as the input stage, thus achieving as large effective input transconductance as that of Si Bipolar or GaAs MESFET. The RGC input configuration isolates the input parasitic capacitance including photodiode capacitance from the bandwidth determination better than common-gate TIA. Test chips were electrically measured on a FR-4 PC board, demonstrating transimpedance gain of 58 dB/spl Omega/ and -3-dB bandwidth of 950 MHz for 0.5-pF photodiode capacitance. Even with 1-pF photodiode capacitance, the measured bandwidth exhibits only 90-MHz difference, confirming the mechanism of the RGC configuration. In addition, the noise measurements show average noise current spectral density of 6.3 pA//spl radic/(Hz) and sensitivity of -20-dBm for a bit-error rate of 10/sup -12/. The chip core dissipates 85 mW from a single 5-V supply.     

Self-Coherent Decision-Feedback-Directed 40-Gb/s DQPSK Receiver

A novel 40-Gb/s differential quadrature phase-shift keying receiver is theoretically proposed, improving direct detection by 4.2 dB for self-phase-modulation-limited single-channel transmission, approaching ideal coherent homodyne performance using a recirculating delay line interferometric integrated-optical circuit front-end combining decision feedback and nonlinear phase-noise compensation