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.

This paper describes a distributed amplifier IC module and a distributed 1 : 2 signal distributor IC module for 40-Gbit/s optical transmission systems. These ICs were designed by the distributed circuit and inverted-microstrip-line design technique and fabricated using 0. 1-µm-gate-length GaAs MESFETs with a multilayer interconnection structure. These were mounted on a thin film multilayer substrate in a chip-size-cavity package by means of a flip-chip-bonding technique that uses transferred microsolder bumps. The amplifier module achieved a 3-dB bandwidth of more than 50 GHz and a gain of 8 dB. The 3-dB bandwidth of a 1 : 2 signal distributor module was 40 GHz and the loss was 2 dB. These modules were demonstrated at 40 Gbit/s and clear eye openings were confirmed.

A procedure for quickly developing highly integrated multifunctional MMICs by using the three-dimensional masterslice MMIC technology has been developed. The structures and advanced features of this technology, such as miniature transmission lines, a broadside coupler, and miniature function block circuits, enable multifunctional MMICs to be quickly and easily developed. These unique features and basic concept of the masterslice technology are discussed and reviewed to examine the advantages of this technology. As an example of quick MMIC development, an amplifier, a mixer, and a down-converter are fabricated on a newly designed master array.

LDD-structure GaAs-MESFETs with WSiN bilayer gate are fabricated adopting neutral buried p-layers formed by 50-keV Be-implantation. fT of 108 GHz and fmax of over 130 GHz are obtained on 0.2-µm gate length. A direct-coupled amplifier IC with bandwidth of 10 GHz are fabricated using 0.4 µm GaAs-MESFETs and achieves a high gain of 20 dB with a minimum NF of 3.2 dB with a power consumption of 365 mW. Moreover, a bandwidth of 20 GHz is predicted for the amplifier IC using 0.2-µm GaAs-MESFETs.

Novel three-dimensional structures for passive elements--inductors, capacitors, transmission lines, and airbridges--have been developed to reduce the area they consume in GaAs MMICs. These structures can be formed with a simple technology by electroplating along the sidewalls of a photoresist. Adopting the new structures, most passive elements in MMICs have been shrunk to less than 1/4 the size of conventional ones.

A new self-aligned recessed-gate GaAs MESFET is developed using RIBE for recess etching. Recess-etching depth can be precisely controlled by RIBE with BCl3 etching gas. Barrier height and ideality factor of the Schottky contact formed on 200-V bias-voltage RIBE etched surface are 0.8 V and 1.2, respectively after 400 annealing. A very short gate-length is realized simply using the sidewall formation and the conventional photolithography. Furthermore, a self-alignment of ohmic electrodes and N+-layers to a gate electrode is realized to minimize the source resistance. The 0.3-µm gate-length MESFET fabricated on a wafer with the carrier concentration of 1.21018 cm-3 grown by MBE shows the transconductance as high as 415 mS/mm.