Misao Yoshimura

A novel resonant-type GaAs SPDT switch IC with low distortion characteristics for 1.9 GHz personal handy-phone system

A GaAs SPDT switch IC operating at a low power supply voltage of 2.7 V has been developed for use in Personal Handy-Phone System in the 1.9 GHz band. In combination with MESFETs with low on-resistance and high breakdown voltage, the resonant-type switch IC utilizes stacked FETs and an additional shunt capacitor at the receiver side in order to realize low insertion loss, high isolation and low distortion characteristics. An insertion loss of 0.55 dB and an isolation of 35.8 dB were obtained at 1.9 GHz. The IC also achieved a second order distortion of -54.3 dBc and an adjacent channel leakage power of -66 dBc at 600 kHz apart from 1.9 GHz at 19 dBm output power.

Refractory WNx/W Self-Aligned Gate GaAs Power Metal-Semiconductor Field-Effect Transistor for 1.9-GHz Digital Mobile Communication System Operating with a Single Low-Voltage Supply

We have developed a refractory WNx /W self-aligned gate GaAs power metal-semiconductor field-effect transistor (MESFET) for use in L-band digital mobile communication systems. This power MESFET operates with high efficiency and low distortion at a gate bias of 0 V and a low drain bias of 2.7 V, because of its small drain knee voltage, high transconductance and sufficient breakdown voltage. This power MESFET is quite promising for a highly efficient linear power amplifier IC operating with a single low-voltage supply. Good output characteristics of the power MESFET with 1 mm gate width were attained for π/4-shifted quadrature phase shift keying (QPSK) modulated input signals in the 1.9-GHz band, such as an output power of 18.4 dBm, a power gain of 19.0 dB and a high power-added efficiency of 26.4% when a sufficiently low adjacent channel leakage power of -58 dBc was obtained.

High-efficiency monolithic GaAs power MESFET amplifier operating with a single low voltage supply for 1.9-GHz digital mobile communication applications

A monolithic GaAs power amplifier IC using refractory WN/sub xW self-aligned gate power MESFETs has been developed for 1.9-GHz digital mobile communication systems, such as the Japanese personal handy phone system. The power amplifier operates with high efficiency and low distortion with a single low voltage supply of 2.7-3.0 V, by virtue of small drain knee voltage, high transconductance and sufficient breakdown voltage of the power MESFET. An output power of 23.7 dBm and a high power-added efficiency of 24.2% were attained at 3 V for 1.9-GHz /spl pi4-shifted QPSK (quadrature phase shift keying) modulated input when adjacent channel leakage power was -58 dBc at 600 kHz apart.<<ETX>>

Buried-Channel WNx/W Self-Aligned GaAs MESFET Process with Selectively Implanted Channel and Undoped Epitaxial Surface Layers for MMIC Applications

The combined process of epitaxy and ion implantation has been developed in the fabrication of a buried-channel WN x /W self-aligned GaAs metal-semiconductor field-effect transistor (MESFET). This MESFET comprises an ion-implanted channel and an undoped GaAs epitaxial surface layer. The ion-implantation technique leads to an IC-oriented process and the epitaxial technique to a buried channel structure. Both ease of isolation and enhanced breakdown voltage were attained, promising monolithic microwave integrated circuits (MMICs) for L-band digital mobile communication systems

A Self-Aligned Gate AlGaAs/GaAs Heterostructure Field-Effect Transistor with an Ion-Implanted Buried-Channel for use in High Efficiency Power Amplifiers

In this paper we report on a self-aligned gate buried-channel Al0.22Ga0.78As/GaAs heterostructure field-effect transistor (BC-HFET). The BC-HFET comprises a selectively ion-implanted channel and an undoped i-AlGaAs surface layer. In order to realize the buried channel heterostructure, a combined process of ion-implantation and epitaxial growth is developed. The post-implantation annealing before the epitaxial growth successfully reduces the interdiffusion at the heterointerface between the ion-implanted GaAs channel and the AlGaAs surface layer. The BC-HFET overcomes the disadvantages of a low breakdown voltage which exists in conventional self-aligned gate MESFETs. The BC-HFET exhibits a high breakdown voltage of 8 V and a high Schottky barrier height of 0.75 eV. The 1-mm-wide power BC-HFET demonstrates an output power of 18.2 dBm and a drain efficiency of 50% at a low adjacent channel leakage power of -59 dBc for a 1.9-GHz π/4-shifted quadrature phase shift keying (QPSK) modulated input, for use as Personal Handy-phone System handsets.