Mitsubishi Electric Corporation

Takao Haruna

Satoshi Suzuki

Kazuya Yamamoto

Yoshinobu Sasaki

Tomoyuki Asada

Takao Moriwaki

Jun Takaso

First and second paths (I,II) are connected in parallel between an input terminal (IN) and an output terminal (OUT). A high-pass filter (HPF) is provided in the first path (I). A low-pass filter (LPF) is provided in the second path (II). A switch (SW-SW) connects one of the high-pass filter (HPF) and the low-pass filter (LPF) to the input terminal (IN) and the output terminal (OUT) and disconnects the other. A transmission line (TL,TL) is provided on the first and second paths (I,II) respectively. A line length of the transmission line (TL,TL) is adjusted such that a resonance caused due to circuit constants of the high-pass filter (HPF) and the low-pass filter (LPF) and capacitance obtained when the switch (SW-SW) is OFF is shifted to a communication frequency band.

Phase shifter

A plurality of transmission lines () are connected to a transistor () and have different characteristic impedances. A plurality of open stubs () are connected to the plurality of transmission lines () respectively. A length of each open stub () is shorter than a length of each transmission line ().

Power amplifier

A power amplifier includes: a transistor having a gate electrode, a source electrode and a drain electrode; a passive component part connected to the gate electrode through a gate wiring; and a harmonic circuit connected between the source electrode and the gate wiring and disposed in a region between the gate electrode and the passive component part and between the source electrode and the gate wiring.

A first amplifier is connected between an input terminal and an output terminal. A first junction point is located between the input terminal and an input of the first amplifier. A second junction point is located between the output terminal and an output of the first amplifier. A second amplifier is connected in parallel with the first amplifier, between the first junction point and the second junction point. A third junction point is located between an output of the second amplifier and the second junction point. A first capacitor and a switch are connected in series between the third junction point and ground. The second junction point is the lowest impedance point along a power amplification path that includes the input terminal, the first amplifier, and the output terminal. The switch is turned off/on when the second/first amplifier is turned on.

A directional coupler includes: a main strip line connected between a first input terminal and a first output terminal and transmitting high-frequency signals; a sub strip line connected between a second input terminal and a second output terminal, located parallel to the main strip line, and electromagnetically coupled to the main strip line; and a first capacitor connected in parallel with the main strip line or the sub strip line, wherein an LC resonant circuit is constituted by inductances of the main strip line and sub strip line and capacitance of the first capacitor, and the LC resonant circuit resonates with respect to a high-frequency signal propagating from the first input terminal to the second output terminal.

Directional coupler

A high frequency power amplifier includes first and second transistors connected in parallel and amplifying a high frequency signal; a first switch connected to outputs of the first and second transistors and which connects an input terminal selectively to first and second output terminals; a third transistor amplifying a signal output from the first output terminal of the first switch; and a second switch having a first input terminal connected to the third transistor, a second input terminal connected to the second output terminal of the first switch, and which selectively connects the first and the second input terminals to an output terminal of the second switch.

High frequency power amplifier

A power amplifier includes: a semiconductor substrate; a preceding-stage amplifying device on the semiconductor substrate, amplifying an input signal; a following-stage amplifying device on the semiconductor substrate, amplifying an output signal of the preceding-stage amplifying device; and an inter-stage matching circuit connecting the preceding-stage amplifying device to the following-stage amplifying device. The preceding-stage amplifying device has a first field effect transistor; the following-stage amplifying device has a heterojunction bipolar transistor; and the inter-stage matching circuit has a capacitance galvanically separating the output terminal of the preceding-stage amplifying device from the input terminal of the following-stage amplifying device.

Growing community of inventors

Tokyo, Japan

Takao Haruna