A monolithic linear power amplifier IC operating with a single low 2.7-V supply has been developed for 1.9-GHz digital mobile communication systems, such as the Japanese personal handy phone system (PHS). Refractory WNx/W self-aligned gate GaAs power MESFETs have been successfully developed for L-band power amplification, and this power amplifier operates with high efficiency and low distortion at a low voltage of 2.7 V, without any additional negative voltage supply, by virtue of small drain knee voltage, high transconductance and sufficient breakdown voltage of the power MESFET. An output power of 23.0 dBm and a high power-added efficiency of 30.8% were attained for 1.9-GHz π/4-shifted QPSK (quadrature phase shift keying) modulated input when adjacent channel leakage power level was less than -60 dBc at 600 kHz apart from 1.9 GHz.

The optimum bias point for a drain mixer operating on low local oscillator (LO) power was investigated. The bias voltage dependence of the required LO power and the conversion gain in the drain mixer was clarified by a simplified nonlinear model which the drain current characteristics around knee voltage is approximated by two straight line segments. It was found that an optimum gate bias voltage Vgs exists for a given applied LO power, and the optimum gate bias voltage moves toward the pinch-off voltage as the injection LO power level decreases. In order to verify the variation of the optimum gate bias voltage, a 60 GHz MMIC drain mixer adopting the optimum gate bias voltage for low LO power level was fabricated. The fabricated drain mixer exhibited a conversion gain of 0 dB with the injection LO power level of 0 dBm. This value of 0 dBm is the best performance yet obtained for a 60 GHz MMIC drain mixer. The measured optimum gate bias voltage was near the pinch-off voltage. This result was in good agreement with the theoretical analysis. The LO power level of a drain mixer has been improved so that it is on a par with that of a gate mixer.

A 60-GHz-band monolithic HEMT amplifier for which BCB thin film layers are adopted on GaAs substrate has been developed. The MMIC utilized a thin film microstrip line for the bias circuit and a coplanar waveguide for the RF circuit. The coplanar waveguide has the advantage of low loss, whereas the thin film microstrip line has the advantage of small size. Two different types of transmission lines were selected to coexist in the monolithic amplifier. As a result, the MMIC achieved high gain over a wider frequency range at a small size. This MMIC had a gain of over 15 dB in a frequency bandwidth of 11 GHz. In particular, the high-frequency characteristics of the transmission lines and the HEMTs were evaluated in detail for the conventional MMIC structure and the new MMIC structure. It was confirmed that this newly developed MMIC using BCB thin film layers is attractive for millimeter-wave applications.

The authors have developed V-band high electron mobility transistor (HEMT) MMICs adopting benzo-cyclo-butene (BCB) thin-film layers on GaAs substrates. Since the BCB thin-film layers, which can change the thickness of arbitrary parts on a circuit, are used for these MMICs, both a thin-film microstrip (TFMS) line, offering the advantages of great flexibility in layout and small size, and a coplanar waveguide (CPW), offering the advantage of low loss, can be used according to the purpose of the MMIC. Here we introduce the four types of V-band MMICs that we fabricated: low noise amplifier (LNA), mixer, voltage controlled oscillator (VCO), and power amplifier (PA). The optimum transmission lines were chosen from the TFMS line and the CPW for these MMICs. Miniaturization of the LNA MMIC and the mixer MMIC were attained by adopting the TFMS line, whereas adoption of the CPW enabled the VCO MMIC to achieve high performance. These results indicate that it is important to choose the optimum transmission line according to the purpose of the circuit function for each MMIC. It was confirmed that these newly developed MMICs using the BCB thin-film dielectric layers are attractive for millimeter-wave applications.

A new glossiness measuring method using the PSD was proposed. This method might be used for the glossiness classification of the specimens such as a high-grade pearls with small gloss-difference, as the substitution of the human visual function.

A system for measuring the low frequency amplitude and phase noises was set-up, with employing a phase sensitive detector and phase-shifter. It is noted that both noises were partly correlated. The phase noise was explained by the transit time fluctuation due to the fluctuating diffusion coefficient. The amplitude noise reduction was demonstrated by applying the inverted output of the phase noise to the amplitude noise.

The author shows experimentally how the nonlinear line transforms the noise spectrum and will discuss 1/f fluctuation phenomena which are widespread in nature. The line is a one-dimensional LC ladder type distributed line with loss, where the capacitor C changes with the line voltage. The experimental and computer-simulated results show a tendency that the white noise is transformed into the 1/f type one along the noise propagation.

The authors measured the temperature dependence of the level of the 1/f noise in carbon-black graft-polymer resistors. A distinct dip is observed in the noise level at a temperature at which the temperature coefficient of the resistance is zero. This is in agreement with our temperature fluctuation model on the 1/f noise in resistors which include a large number of small conducting spots.