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 three-dimensional MMIC structure and an ultra-wideband miniature MMIC balun are proposed. The MMIC is a combined structure of multilayer MMICs and U-shaped micro-wires. This technology effectively reduces chip size and enhances MMIC performance. The proposed balun is constructed with three narrow conductors located side by side. The U-shaped micro-wire technology is employed to reduce the insertion loss and chip size. 1.51 dB insertion loss over 10 to 30 GHz, and 2 dB and 5 degrees of amplitude and phase balances over 5 to 35 GHz have been obtained. The intrinsic area of the balun is only 450800 µm, about 1/5 to 1/3 the area of recently reported miniaturized MMIC baluns.

A 0.1-µm gate-length GaAs MESFET technology is reported. A 48.3-GHz dynamic-frequency divider, and an amplifier with 20-dB gain and 17.5-GHz bandwidth are successfully fabricated by integrating over-100-GHz-cut-off frequency MESFETs using a new lightly-doped drain structure with a buried p-layer (BP-LDD) device structure.

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.

A high-speed potential of an n+-Ge gate AlGaAs/GaAs MISFET has been confirmed by a ring oscillator and a frequency divider performances. The circuit was based on SCFL with 1.0 µm gate-length MISFET's. The delay time was 42.4 ps with a power dissipation of 8.9 mW/gate. A maximum toggle frequency of 11.3 GHz with a power dissipation of 219 mW per T-F/F has been achieved at room temperature.