A monolithic four-stage low-noise amplifier (LNA) was successfully demonstrated for direct broadcast satellite (DBS) down-converters using 0.3 µm gate pulse-doped GaAs MESFET's This paper presents the design and test results of the LNA. The key feature of the research is a detailed demonstration of the difference between a noise figure of the four-stage LNA and an optimal noise figure of an employed FET with simulation and experiments. This LNA shows VSWR's of below 1.5: 1 as well as a noise figure of 1.1 dB and a gain of 28 dB at 12 GHz. To the best of our knowledge, it is the lowest noise figure reported so far in 12 GHz-band MMIC amplifiers. In the power characteristics, a 1 dB compression point (P1dB) of 10 dBm and a third order intercept point (IP3) of 19 dBm were shown.

Ultrahigh speed and low crosstalk four-channel receiver optoelectronic integrated circuit (OEIC) arrays comprising GaInAs pin PDs and A1InAs/GaInAs HEMTs have been successfully fabricated on an InP substrate. These arrays were designed to have good crosstalk characteristics which are the most critical issue in array devices. The resistive-load OEIC arrays exhibited high speed operation up to 5 Gb/s and low crosstalk of less than -38 dB between whole adjacent channels over entire frequency range below 4.0 GHz. The average sensitivity of resistive-load OEIC arrays was -18.5 dBm at 3 Gb/s for a bit-error-rate of 10-9 over four channels. Good uniformity of device characteristics was obtained over 2-inch InP wafer. These results suggest that receiver OEIC arrays are quite promising for the application to high-speed multi-channel optical interconnections.

The characteristics of voltage-resonant dc-dc converters have already been analyzed and described. However, in the conventional analysis, the inductance of the reactor is assumed to be infinity and the loss resistance of the power circuit is not taken into account. Also, in some cases, the averaging method is applied to analyze the resonant dc-dc converters as well as the pwm dc-dc converters. Consequently, the results from conventional analysis are not entirely in agreement with the experimental ones. This paper presents a general design-oriented analysis of the buck-boost type voltage-resonant dc-dc converter in the continuous and discontinuous modes of the reactor current. In this analysis, the loss resistance in each part of the power circuit, the inductance of the reactor, the effective value (not mean value) of the power loss, and the energy-balance among the input, output and internal-loss powers are taken into account. As a result, the behavior and characteristics of the buck-boost type voltage-resonant dc-dc converter are fully explained. It is also revealed that there is a useful mode in the discontinuous reactor current region, in which the output voltage can be regulated sufficiently for the load change from no load to full load and for the relatively large change of the input voltage, and then the change in the switching frequency can be kept relatively small.

A new acousto-optic tunable filter utilizing collinear acousto-optic interaction along the direction near to the optic axis is proposed and demonstrated by using LiNbO3 crystal. This near axis interaction lowers the driving frequency and also expands the angular aperture in the ordinary plane. The acousto-optic figure of merit M2 (p2/ρv3) of this filter is 7.510-18 sec3/g and tuning from 700 nm to 420 nm can be obtained by changing the acoustic frequency from 56 MHz to 119 MHz. At 514.5 nm the filter bandwidth of 1.1 nm and the angular aperture of about 6 in the ordinary plane have been obtained.