High speed GaAs ICs (Integrated Circutis) using FETs (Field Effect Transistors) are reported. As the fabricating techniques, ion implantation processes for both 0.5 µm and 0.2 µm gate FETs using W/Al refractory metal and 0.2 µm recessed gate process with MBE grown epitaxial wafers are shown. These fabrication processes are selected depending on the circuit speed and the integration level. The outline of the circuit design and the examples of ICs, which are developed for 10 Gb/s optical communication systems, are also shown with the obtained characteristics.

This paper describes the architecture and the performances of a GaAs 88 self-routing switch LSI for ATM switching system. The communication system such as broadband integrated sevices digital network (B-ISDN) requires the hardware switch LSI which exchanges packet cells at a date rate up to several Gb/s. GaAs LSIs are suitable for such application because of its high speed operation and low power dissipation. To clarify the feasibility of GaAs LSI, an 88 self-routing switch LSI is fabricated using 0.5 µm gate GaAs MESFETs and its oerformances are examined. This LSI consists of a switching network for exchanging the packet cells and the "NEMAWASHI" network which detects the cell destined to the same output port. The basic network architecture is a self-routing switch using Batcher-Banyan network. This network consists of basic 22 switch element. Since each element switches the route accorging to the destination of the input cells, self-routing operation is performed without the external circuit for routing control. The LSI is fabricated using 0.5 µm gate GaAs MESFETs. 7003 logic gate are integrated on the chip of 8.2 mm7.4 mm. To reduce the impedance of ground line on the chip and to obtain the enough noise margin, the third level interconnection with low sheet resistance is implemented. As the results of functional evalution, the full function of switching network and "NEMAWASHI" network are verified. Maximum operation speed of 1 GHz is obtained.

Multilayered volumetric composite right/left handed metamaterial structures are investigated. The present structure is composed of conducting mesh plates and dielectric layers including dielectric resonators. The 2-D composite right/left handed metamaterial structure is designed for the in-plane propagation. Propagation mode analysis was made for the volumetric structure under the periodic boundary condition along the normal to the layers as well as for finite number of layered type for comparison. The negative-refractive-index planar lenses were designed and fabricated for the demonstration. It is found from the numerical simulation that the beam focusing through the planar lens with large number of layers is clearly confirmed in both magnitude and phase distribution of the fields. On the other hand, for small number of layers, the beam spot is not found in the magnitude distribution due to the effect of discontinuities between air and designed structure at the top and bottom surfaces, but is still found in the phase distribution. The effect of number of stacked layers on the propagation characteristics is discussed by comparing the numerical simulation results with the measurement.

Beam steering of leaky wave radiation from a nonreciprocal composite right/left handed transmission line with a ferrite substrate is proposed. The nonreciprocal phase constants of the line were tuned by changing the applied DC magnetic field normal to the ferrite substrate. In the numerical simulation and the experiment, the nonreciprocal phase characteristics and leaky wave radiation are investigated for the ferrite substrate with the magnetization not only in the saturated region, but also in the unsaturated region. The numerical simulation results are in good agreement with the measurement. It is confirmed that the beam directions of the obliquely unidirectional leaky wave radiation for two different power directions are continuously tunable.