In a semiconductor device using an emitter top heterojunction bipolar transistor having a planar shape in a ring-like shape, a structure is provided in which a base electrode is present only on an inner side of a ring-like emitter-base junction region. This allows reduction of base/collector junction capacitance per unit emitter area, whereby a semiconductor device having high power adding efficiency and high power gain suitable for a power amplifier can be realized. Further, in a multistage power amplifier including first and second amplifier circuits each having one or more of bipolar transistors, a bipolar transistor in the first amplifier circuit uses an emitter having a planar shape in a rectangular shape, and a bipolar transistor in the second amplifier circuit uses an emitter having a ring-like shape and a base electrode only on the inner side of the emitter.

 
Web www.patentalert.com

< Semiconductor apparatus with monocrystal insulating film

< Pseudomorphic high electron mobility field effect transistor with high device linearity

> Sheet-type -FeSi2 element, and method and device for manufacturing the same

> Capacitors having a capacitor dielectric layer comprising a metal oxide having multiple different metals bonded with oxygen

~ 00207