Fujitsu Corporation

Transphorm Japan, Inc.

Masato Nishimori

Toshihide Kikkawa

Atsushi Yamada

Tadahiro Imada

Toshihiro Ohki

Tatsuya Hirose

Kozo Makiyama

Ikuo Soga

Masayuki Hosoda

A power amplifier includes a main amplifier, an auxiliary amplifier, and a control circuit. The main amplifier is configured to amplify input power, and the auxiliary amplifier is configured to amplify the input power when the input power exceeds a certain level. The control circuit, which is provided between a source of the main amplifier and a ground, is configured to control a source potential of the main amplifier so as to increase the source potential when the input power reaches at least a certain value.

Power amplifier, semiconductor integrated circuit, and method of controlling the power amplifier

A power amplification apparatus which is a Doherty power amplification apparatus includes a main amplifier configured to amplify an input signal, and an auxiliary amplifier configured to amplify the input signal when a level of the input signal is higher than a predetermined level. The power amplification apparatus includes an auxiliary amplifier threshold value shift detector configured to detect a threshold value shift in the auxiliary amplifier; and an auxiliary amplifier bias voltage adjustment circuit configured to adjust a bias voltage of the auxiliary amplifier based on the detected threshold value shift in the auxiliary amplifier.

Power amplification apparatus and method for controlling power amplification apparatus

A semiconductor device is configured including a p-type back barrier layer provided over a substrate and formed from a p-type nitride semiconductor in which Mg or Zn is doped, a nitride semiconductor stacked structure provided over the p-type back barrier layer, the nitride semiconductor stacked structure including an electron transit layer and an electron supply layer, a source electrode, a drain electrode and a gate electrode provided over the nitride semiconductor stacked structure, and a groove extending to the p-type back barrier layer.

Semiconductor device, fabrication method for semiconductor device, power supply apparatus and high-frequency amplifier

A semiconductor device includes a carrier transit layer including a first region and second and third regions having a density of a donor impurity element higher than that of the first region, an InAlGaN (0&#x3c;X&#x3c;1, 0&#x3c;Y&#x3c;1, 0&#x3c;X+Y&#x2264;1) carrier supply layer provided over the carrier transit layer and having a density of a donor impurity element lower than that of the second and third regions, a source electrode provided over the second region, a drain electrode provided over the third region, and a gate electrode provided over the carrier supply layer between the source electrode and the drain electrode.

3-5 device with doped regions and method of fabricating

A semiconductor device includes a first semiconductor layer of a first conductivity type formed on one side of a semiconductor substrate; a second semiconductor layer of a second conductivity type formed on the first semiconductor layer; a third semiconductor layer of the first conductivity type formed on the second semiconductor layer; an opening part formed by removing part of the first to third semiconductor layers; a gate insulating film formed so as to cover an inner wall of the opening part; a gate electrode formed inside the opening part via the gate insulating film; a source electrode formed on a surface of the third semiconductor layer; a drain electrode connected to a part corresponding to the gate electrode on another side of the semiconductor substrate; and a fourth electrode formed on the another side of the semiconductor substrate at a part corresponding to the source electrode.

Semiconductor device and manufacturing method of semiconductor device

A semiconductor device includes an electron transit layer configured to be formed on a substrate; an electron supply layer configured to be formed on the electron transit layer; an upper surface layer configured to be formed on the electron supply layer; a gate electrode configured to be formed on the electron supply layer or the upper surface layer; a source electrode and a drain electrode configured to be formed on the upper surface layer; and first conductivity-type regions configured to be formed in the upper surface layer and the electron supply layer immediately below regions where the source electrode and the drain electrode are formed. The electron supply layer is formed of a nitride semiconductor including In. The upper surface layer is formed of a material including a nitride of one or more elements selected among B, Al, and Ga.

Manufacturing method of semiconductor device including indium

A semiconductor device includes: a first nitride semiconductor layer formed over a substrate; a second nitride semiconductor layer formed over the first nitride semiconductor layer; element isolation regions formed in a part of the second nitride semiconductor layer and the first nitride semiconductor layer; a gate electrode, source electrodes, and a drain electrode formed over the second semiconductor layer and the element isolation regions; and a drain field plate formed in such a manner as to project from upper portions of side surfaces of the drain electrode.

Semiconductor device and method for manufacturing semiconductor device

A compound semiconductor device includes as compound semiconductor layers: a first layer; a second layer larger in band gap than the first layer, formed above the first layer; a third layer having a p-type conductivity type, formed above the second layer; a gate electrode formed above the second layer via the third layer; a fourth layer larger in band gap than the second layer, formed to be in contact with the third layer above the second layer; and a fifth layer smaller in band gap than the fourth layer, formed to be in contact with the third layer above the fourth layer.

Compound semiconductor device and method of manufacturing the same

A semiconductor device includes a substrate, a carrier transit layer disposed above the substrate, a compound semiconductor layer disposed on the carrier transit layer, a source electrode disposed on the compound semiconductor layer, a first groove disposed from the back of the substrate up to the inside of the carrier transit layer while penetrating the substrate, a drain electrode disposed in the inside of the first groove, a gate electrode located between the source electrode and the first groove and disposed on the compound semiconductor layer, and a second groove located diagonally under the source electrode and between the source electrode and the first groove and disposed from the back of the substrate up to the inside of the carrier transit layer while penetrating the substrate.

Method for manufacturing a compound semiconductor device

A semiconductor device includes a buffer layer that is disposed over a substrate, a high-resistance layer that is disposed over the buffer layer, the high-resistance layer being doped with a transition metal for achieving high resistance, a low-resistance region that is disposed in a portion of the high-resistance layer or over the high-resistance layer, the low-resistance region being doped with an impurity element for achieving low resistance, an electron travel layer that is disposed over the high-resistance layer including the low-resistance region, an electron supply layer that is disposed over the electron travel layer, a gate electrode that is disposed over the electron supply layer, and a source electrode and a drain electrode that are disposed over the electron supply layer.

Growing community of inventors

Atsugi, Japan

Masato Nishimori