A high-gain wide-band amplifier IC module is needed for high-speed communication systems. However, it is difficult to expand bandwidth and maintain stability. This is because small parasitic influences, such as bonding-wire inductance or the capacitance of the package, become large at high frequencies, thus degrading performance or causing parasitic oscillation. In this paper, a new design procedure is proposed for the high-gain and wide-band IC module, using stability analysis and a unified design methodology for IC's and packages. A multichip structure is developed using stability analysis and the requirements for stable operation are determined for each IC chip, package, and interface condition between them. Furthermore, to reduce the parasitic influences, several improvements in the interface and package design are clarified, such as wide-band matching and LC resonance damping. IC design using effective feedback techniques for enlarging the bandwidth are also presented. The IC's are fabricated using 0.2-µm GaAs MESFET IC technology. To verify the validity of these techniques, an equalizer IC module for 10-Gb/s optical communication systems was fabricated achieving a gain of 36 dB and a bandwidth of 9 GHz.

We demonstrated the uniformity and stability as well as the high breakdown voltage of 0.1-µm-gate InP HEMTs with a double recess structure. To overcome the drawbacks regarding the uniformity and stability in the double recess structure, an InP passivation layer that functions as an etch-stopper and a surface passivator was successfully applied to the structure. It was confirmed that there was no degradation in the uniformity and stability of device performance for the double recess HEMTs that had the breakdown voltages in the on-state and off-state improved by a factor of 1.6.

Ultrahigh-speed integrated-circuit technology is one of the keys to achieving ultralarge-capacity optical communication systems. Technological breakthroughs in circuit and packaging design as well as improved transistor performance are needed to reach the over-40-Gbit/s operating region. This paper describes a 0.1-µm gate InP HEMT, novel circuit design, and broadband packaging technologies developed to boost the circuit speed. We used these technologies to make 40-Gbit/s lightwave communication ICs. This paper also describes the problems and challenges toward 100-Gbit/s operation.

A 50-Gbit/s demultiplexer IC module that uses 0.1-µm InAlAs/InGaAs/InP HEMTs is reported. The maximum error-free operation bit-rate of a fabricated module is 50 Gbit/s, and a wide phase margin of 170 degrees is obtained at 43 Gbit/s. 50-Gbit/s demultiplexing is the fastest performance of all packaged demultiplexer ICs yet reported.

The authors report ultra-high-speed digital IC modules that use 0.1-µm InAlAs/InGaAs/InP HEMTs for broadband optical fiber communication systems. The multiplexer IC module operated at up to 70 Gbit/s, and error-free operation of the decision IC module was confirmed at 50 Gbit/s. The speed of each module is the fastest yet reported for its kind.

Self-aligned T-shaped Au/WSiN gate i-InGaP/n-InGaAs/i-GaAs heterostructure MESFETs with a BP-LDD structure were developed for application to microwave and millimeter-wave communication systems. Owing to the use of tilted-angle n+-ion-implantation, symmetric and asymmetric structures FETs can be fabricated on the same chip and low noise, high breakdown voltage, and high power gain can be attained simultaneously. The fabricated symmetric FETs, with a gate length of 0. 13 µm, exhibit a current cutoff frequency of more than 70 GHz and a minimum noise figure as low as 1. 0 dB at 20 GHz, while the gate-drain breakdown voltage is more than 8 V and the MSG is as high as 7. 8 dB at 60 GHz in the asymmetric FETs on the same chip. V-band MMIC amplifiers fabricated using symmetric FETs exhibit a gain of more than 9 dB and a noise figure of 6 dB over the 50 to 60 GHz frequency range.