Mitsubishi Denki Kabushiki Kaisha

Mitsubishi Electric Corporation

Kyocera Corporation

Teruyuki Shimura

Shinichi Miyakuni

Manabu Katoh

Satoshi Suzuki

Kazuya Yamamoto

Ryo Hattori

Takeshi Miura

Tadashi Takagi

Kazuhiko Nakahara

Kazutomi Mori

Tomoyuki Asada

Masayuki Sakai

Kousei Maemura

Masatoshi Nakayama

Hirofumi Nakano

Miyo Miyashita

Hiroshi Matsuoka

Shintaro Shinjo

Takayuki Katoh

Akira Ohta

Takayuki Matsuzuka

Tomoki Oku

Takuji Sonoda

Shinji Isoyama

Kazuhiro Iyomasa

Naohito Yoshida

Shigeru Mitsui

Saburo Takamiya

Toshio Okuda

Katsurou Nakamata

Hiroaki Seki

Provided is a high frequency amplifier including two amplifying elements of different element sizes connected in parallel and switching the amplifying elements in accordance with a level of output power. In particular, the high frequency amplifier includes an output matching circuit for matching to characteristic impedance (50 ohms) both when the output power is high and low, and increasing impedance when the turned-off amplifying element is viewed from a connection node on an output side of the two amplifying elements. Consequently, characteristics such as high output power and high efficiency can be achieved and it is possible to prevent an amplified high frequency signal from passing around to a matching circuit on a turned-off amplifying element side.

High frequency amplifier

A power amplifier according to the present invention is operated by switching a main power amplifier and a subsidiary power amplifier. The idle current of the subsidiary power amplifier is smaller than the idle current of the main power amplifier. Each of the main power amplifier and the subsidiary power amplifier has a former amplification element for amplifying RF signals, a latter amplification element for amplifying output signals from the former amplification element, a former bias circuit for driving the former amplification elements, and a latter bias circuit for driving the latter amplification elements, respectively. The interval between the latter amplification element of the main power amplifier and the latter amplification element of the subsidiary power amplifier is not more than 100 &#x3bc;m. The interval between the latter amplification element of the main power amplifier and the latter bias circuit of the subsidiary power amplifier is not less than 200 &#x3bc;m.

Power amplifier

Disclosed is an output overvoltage protection circuit for a power amplifier having a plurality of stages, which comprises a monitor circuit for monitoring an output overvoltage of an output transistor in the final stage of the power amplifier and allowing a current to flow therethrough in response to the monitored output overvoltage, and a current mirror circuit for supplying a current proportional to the current from the monitor circuit in such a manner that the base bias of the first-stage transistor of the power amplifier is reduced in response to the current supplied from the current mirror circuit, to reduce the output of the final-stage output transistor.

Output overvoltage protection circuit for power amplifier

A high-frequency semiconductor device according to the present invention achieves improvements in degradation of noise characteristics and a reduction in gain, and an improvement in reduction in power efficiency while suppressing a concentration of a current to multifinger HBTs. In the multifinger HBTs constituting a first stage and an output stage of an amplifier, basic HBTsthat constitute the multifinger HBTcorresponding to the first stage, are each made up of an HBTand an emitter resistorconnected to the corresponding emitter of the HBT, whereas basic HBTsthat constitute the multifinger HBTcorresponding to the output stage, are each comprised of an HBTand a base resistorconnected to the corresponding base of the HBT. The high-frequency semiconductor device according to the present invention is useful as a high output power amplifier used in satellite communications, ground microwave communications, mobile communications, etc.

High-frequency semiconductor device

A high frequency module according to the present invention comprises a laminate board having a plurality of dielectric layers ( to ) stacked one on another, a branch filter circuit (DIP ) for separating a plurality of transceiver systems from each other, switch circuits (SW , SW ) for switching the respective transceiver systems between transmitter branches (TX) and receiver branches (RX), power amplifiers (AMP , AMP ) each comprising a matching circuit (MAT , MAT ) and a high frequency amplification semiconductor device for amplifying a transmission signal having a frequency within a pass band of each of the transmitter branches (TX), and couplers (COP , COP ) for monitoring outputs.

High frequency module having a laminate board with a plurality of dielectric layers

Heterojunction bipolar transistor and method for producing the same

A heterojunction bipolar transistor is provided with a ballast resistor layer in an emitter layer which prevents the current amplification factor .beta. from decreasing. The n-GaAs carrier supply layer having a specified carrier concentration is formed between the ballast resistor layer and the n-AlGaAs layer.

Heterojunction bipolar transistor with ballast resistor

A bias circuit for a bipolar transistor includes a constant voltage source connected to a base electrode of the bipolar transistor; and a resistor connected in series between the constant voltage source and the base electrode of the bipolar transistor. By selecting an appropriate resistance for this resistor, the bias point moves due to a change in the voltage drop across the resistor. The change occurs because the base current flowing through the resistor changes, whereby the operating class of the transistor changes, resulting in a high efficiency at a desired output power.

Bias circuit for bipolar transistor

A microwave power amplifier having n stages (n is an integer of at least two), which uses bipolar transistors as amplifying elements. Grounded electrodes, bias applying methods, and bias values of the bipolar transistors of the respective stages are set so that phase rotations of output powers of bipolar transistors of m stages (m is an integer of 1.ltoreq.m.ltoreq.n-1) among the n stages are canceled by phase rotation of at least one of the other bipolar transistors of the (n-m) stages. Therefore, the total phase rotation of the power amplifier can be neutralized, resulting in a microwave power amplifier having excellent distortion characteristics.

Microwave power amplifier

A semiconductor device includes a semiconductor substrate having opposite front and rear surfaces; a semiconductor element disposed on the front surface of the semiconductor substrate and including an electrode; a PHS for dissipating heat generated in the semiconductor element, the PHS including a metal layer and disposed on the rear surface of the semiconductor substrate; a via-hole including a through-hole penetrating through the semiconductor substrate from the front surface to the rear surface and having an inner surface, and a metal disposed in the through-hole and contacting the PHS; and an air-bridge wiring including a metal film and having first and second portions, the air-bridge contacting the electrode of the semiconductor element at the first portion and contacting the metal of the via-hole at the second portion. Therefore, heat produced in the semiconductor element is transferred to the PHS not only through the semiconductor substrate just under the element but also through the air-bridge wiring and the via-hole, whereby the heat dissipating property of the device is significantly improved.

Semiconductor device including plated heat sink and airbridge for heat

An electrode lead of a transistor extends beyond other electrode leads of the transistor, is disposed adjacent to the corresponding electrode, and is disposed outside the other electrode leads for heat radiation. A wider part of the electrode lead may have a via hole or a thick metal plating for heat radiation. Further, the electrode is preferably grounded and is connected to an external input terminal to which heat is transferred.

Hybrid transistor structure with widened leads for reduced thermal

A bipolar transistor circuit element includes a semiconductor substrate; successively disposed on the substrate, a base layer, an emitter layer, and a collector layer; a bipolar transistor formed from parts of the collector, base, and emitter layers and including a base electrode electrically connected to the base layer and a base electrode pad for making an external connection to the base layer; a base ballasting resistor formed from a part of the base layer isolated from the bipolar transistor and electrically connecting the base electrode to the base electrode pad; and a base parallel capacitor connected in parallel with the base ballasting resistor wherein the base parallel capacitor includes part of the base input pad, a dielectric film disposed on part of the base electrode pad, and a second electrode disposed on the dielectric layer opposite the base electrode pad and electrically connected to the emitter electrode of the bipolar transistor. The base ballasting resistor has a high resistance relative to an emitter ballasting reactor so that it can be easily mass produced with good uniformity and yield.

Bipolar transistor circuit element having base ballasting resistor

A semiconductor device includes a semiconductor substrate; a first active layer disposed on the semiconductor substrate; a second active layer disposed on the first active layer; a first electrode including a lower stage disposed on the second active layer and an upper stage disposed on the lower stage and having an overhanging portion protruding from the lower stage; an insulating film continuously covering a surface of the second active layer, a side surface of the lower stage of the first electrode, and a lower surface and a side surface of the overhanging portion of the upper stage; and a second electrode disposed on the surface of the first active layer at opposite sides of the second active layer, self-aligned with the second active layer. The distance between the second electrode and the second active layer is minimized and the thickness of the second electrode can be about 7000 .ANG., minimizing the resistance of the first active layer and improving high frequency characteristics. Electrical separation between the first and second active layers can be achieved reliably. Recombination at the surface of the second active layer is suppressed.

Compound semiconductor bipolar transistor

A high power bipolar transistor includes bipolar transistors disposed on a substrate; a signal line including a pad for inputting a driving signal and a signal transmission line continuous with the pad commonly connecting base electrodes of the bipolar transistors; and a bypass line having a first end connected to the signal transmission line proximate to the pad and a second end connected to the signal transmission line remote from the pad. Approximately equal powers are supplied to the transistors connected to any position on the base feed line so that the operation of the respective transistors is uniform, improving output power and efficiency.

High power bipolar transistor device

A heterojunction bipolar transistor includes a compound semiconductor substrate, a collector layer disposed on the compound semiconductor substrate, a base layer disposed on the collector layer, the base layer being a semiconductor having a band gap energy and including an internal base region and an external base region, and an emitter layer disposed on the base layer and being a semiconductor having a band gap energy larger than the band gap energy of the semiconductor of the base layer. The base layer is larger in area than the emitter layer by the external base region. The external base region is sandwiched by insulating films at the external base region. Therefore, without ion-implantation to make the resistance of the collector layer below the external base region higher, i.e., without increasing the base resistance, the base-collector capacitance is reduced, resulting in an HBT having an improved high frequency gain.

Growing community of inventors

Itami, Japan

Teruyuki Shimura