Abstract: In one example, a signal processing circuit including a directional coupler and a termination part is disclosed. The directional coupler includes a main line as a transmission path of an RF signal and a sub-line constituting a coupled line together with the main line. The termination part includes devices connectable between ground and a first port at an end of the sub-line. The signal processing circuit switches, depending on a frequency of the RF signal, the devices of the termination part to be connected to the first port. The phase of a return signal of a signal input as a coupling signal to the termination part via the first port is opposite to the phase of an isolation signal supplied to a second port at the other end of the sub-line and connected to an output port of the coupling signal.

Abstract: In one example, a signal processing circuit including a directional coupler and a termination part is disclosed. The directional coupler includes a main line as a transmission path of an RF signal and a sub-line constituting a coupled line together with the main line. The termination part includes devices connectable between ground and a first port at an end of the sub-line. The signal processing circuit switches, depending on a frequency of the RF signal, the devices of the termination part to be connected to the first port. The phase of a return signal of a signal input as a coupling signal to the termination part via the first port is opposite to the phase of an isolation signal supplied to a second port at the other end of the sub-line and connected to an output port of the coupling signal.

Abstract: In one example, a signal processing circuit including a directional coupler and a termination part is disclosed. The directional coupler includes a main line as a transmission path of an RF signal and a sub-line constituting a coupled line together with the main line. The termination part includes devices connectable between ground and a first port at an end of the sub-line. The signal processing circuit switches, depending on a frequency of the RF signal, the devices of the termination part to be connected to the first port. The phase of a return signal of a signal input as a coupling signal to the termination part via the first port is opposite to the phase of an isolation signal supplied to a second port at the other end of the sub-line and connected to an output port of the coupling signal.

Abstract: In one example, a signal processing circuit including a directional coupler and a termination part is disclosed. The directional coupler includes a main line as a transmission path of an RF signal and a sub-line constituting a coupled line together with the main line. The termination part includes devices connectable between ground and a first port at an end of the sub-line. The signal processing circuit switches, depending on a frequency of the RF signal, the devices of the termination part to be connected to the first port. The phase of a return signal of a signal input as a coupling signal to the termination part via the first port is opposite to the phase of an isolation signal supplied to a second port at the other end of the sub-line and connected to an output port of the coupling signal.

Abstract: A high-frequency device having a switching circuit including a semiconductor substrate; a first high-frequency input/output terminal; a second high-frequency input/output terminal; a control signal input terminal; a power terminal; a ground terminal; an insulating portion disposed on a main surface of the semiconductor substrate; and a voltage-applying electrode for applying a predetermined positive voltage from the power electrode to the semiconductor substrate, wherein the switching circuit includes a field-effect transistor disposed in an active region of the semiconductor substrate.

Abstract: A high-frequency device having a switching circuit including a semiconductor substrate; a first high-frequency input/output terminal; a second high-frequency input/output terminal; a control signal input terminal; a power terminal; a ground terminal; an insulating portion disposed on a main surface of the semiconductor substrate; and a voltage-applying electrode for applying a predetermined positive voltage from the power electrode to the semiconductor substrate, wherein the switching circuit includes a field-effect transistor disposed in an active region of the semiconductor substrate.

Abstract: A high-frequency device having a switching circuit including a semiconductor substrate; a first high-frequency input/output terminal; a second high-frequency input/output terminal; a control signal input terminal; a power terminal; a ground terminal; an insulating portion disposed on a main surface of the semiconductor substrate; and a voltage-applying electrode for applying a predetermined positive voltage from the power electrode to the semiconductor substrate, wherein the switching circuit includes a field-effect transistor disposed in an active region of the semiconductor substrate.

Abstract: A high-frequency device having a switching circuit including a semiconductor substrate; a first high-frequency input/output terminal; a second high-frequency input/output terminal; a control signal input terminal; a power terminal; a ground terminal; an insulating portion disposed on a main surface of the semiconductor substrate; and a voltage-applying electrode for applying a predetermined positive voltage from the power electrode to the semiconductor substrate, wherein the switching circuit includes a field-effect transistor disposed in an active region of the semiconductor substrate.

Abstract: A high-frequency device includes at least an insulating substrate, a semiconductor substrate, a switching circuit, and an electrode. The semiconductor substrate is on the insulating substrate. A switching circuit is within an active region of the semiconductor substrate. The electrode is in contact with the semiconductor substrate such that a voltage signal can be applied to the semiconductor substrate via the electrode.

Abstract: A high frequency integrated circuit equipped with an electrostatic protection device provided with a field effect transistor as an electrostatic protection device at the input and output of a high frequency integrated circuit, having excellent high frequency characteristics, and making an ESD withstand voltage large, having a high frequency circuit 11 having input/output terminals and an enhancement type field effect transistor 13 formed on a compound semiconductor substrate and provided in said high frequency circuit, having one terminal of the input/output terminals connected to the input/output terminals of the high frequency circuit, having the other terminal connected to a first reference potential, and having a gate connected via a resistor 14 to a second reference potential, and making an impedance of the field effect transistor 13 low for ESD protection when noise or a high voltage pulse is applied from the input/output terminals.

Abstract: A high-frequency device having a switching circuit including a semiconductor substrate; a first high-frequency input/output terminal; a second high-frequency input/output terminal; a control signal input terminal; a power terminal; a ground terminal; an insulating portion disposed on a main surface of the semiconductor substrate; and a voltage-applying electrode for applying a predetermined positive voltage from the power electrode to the semiconductor substrate, wherein the switching circuit includes a field-effect transistor disposed in an active region of the semiconductor substrate.

Abstract: A high-frequency device having a switching circuit includes a compound semiconductor substrate; a first high-frequency input/output terminal; a second high-frequency input/output terminal; a control signal input terminal; a power terminal; a ground terminal; an insulating portion disposed on one main surface of the compound semiconductor substrate; and a voltage-applying electrode for applying a predetermined positive voltage from the power electrode to the compound semiconductor substrate, wherein the switching circuit includes a field-effect transistor disposed on the other main surface of the active region of the compound semiconductor substrate.

Abstract: A high frequency integrated circuit equipped with an electrostatic protection device provided with a field effect transistor as an electrostatic protection device at the input and output of a high frequency integrated circuit, having excellent high frequency characteristics, and making an ESD withstand voltage large, having a high frequency circuit 11 having input/output terminals and an enhancement type field effect transistor 13 formed on a compound semiconductor substrate and provided in said high frequency circuit, having one terminal of the input/output terminals connected to the input/output terminals of the high frequency circuit, having the other terminal connected to a first reference potential, and having a gate connected via a resistor 14 to a second reference potential, and making an impedance of the field effect transistor 13 low for ESD protection when noise or a high voltage pulse is applied from the input/output terminals.

Abstract: A high-frequency device having a switching circuit includes a compound semiconductor substrate; a first high-frequency input/output terminal; a second high-frequency input/output terminal; a control signal input terminal; a power terminal; a ground terminal; an insulating portion disposed on one main surface of the compound semiconductor substrate; and a voltage-applying electrode for applying a predetermined positive voltage from the power electrode to the compound semiconductor substrate, wherein the switching circuit includes a field-effect transistor disposed on the other main surface of the active region of the compound semiconductor substrate.

Abstract: An antenna switching circuit and communication system capable of reducing a high-order harmonic component radiated from the antenna used for transmission and reception. A fundamental wave passes through a signal transmission line between an antenna switch and a transmitting circuit, a filter circuit is connected for reflecting the high-order harmonic component, the high-order harmonic component generated due to linear distortion of the antenna switch is propagated toward the antenna and the transmitting circuit, the high-order harmonic component is reflected at a node of the filter circuit, and the reflected signal is propagated toward the antenna through the antenna switch. By suitably controlling a reflection characteristic of the filter circuit and a line of the signal transmission line, the high-order harmonic components on the transmission line are cancelled out and the high-order harmonic component from the antenna can be decreased.

Abstract: A high-frequency circuit, wherein there is provided a switching transistor connected between an input terminal and an output terminal, with a gate electrode connected to a control terminal via a resistance element, and with an effective gate portion of the gate electrode divided into a plurality of sections, and arrangement is made of additional capacitance elements added in parallel to a capacitance between a gate and a source or drain of the switching transistor at positions in proximity to one ends of at least two effective gate sections of the plurality of effective gate sections. Preferably, there is provided a short-circuiting transistor similarly having an additional capacitance element between the output terminal Tout and a reference voltage supply line.

Abstract: In a switching circuit, low insertion loss and enough isolation can be ensured at a desired frequency at the same time. An inductor is externally connected in parallel with the path between the drain and source of each of field-effect transistors built in a switching integrated circuit, and the inductor and the OFF capacitance of the field-effect transistor are made to generate parallel resonance. At this time, by suitably adjusting the inductance, low insertion loss and enough isolation are ensured at a desired frequency at the same time.

Abstract: Switches are provided on the input and output side of an amplification stage in a signal switching circuit provided in a signal transmission line, and another signal is provided so that a signal can be transmitted directly. Further, a switching circuit is formed from FET elements, which are controlled to be switched on/off by control signals to assure a high isolation.

Abstract: In a switching circuit, low insertion loss and enough isolation can be ensured at a desired frequency at the same time. An inductor is externally connected in parallel with the path between the drain and source of each of field-effect transistors built in a switching integrated circuit, and the inductor and the OFF capacitance of the field-effect transistor are made to generate parallel resonance. At this time, by suitably adjusting the inductance, low insertion loss and enough isolation are ensured at a desired frequency at the same time.

Abstract: In a switch semiconductor integrated circuit, a switch for high frequency signal is constituted by four field-effect transistor stages connected in series to the first to fourth signal paths arranged in a ring shape and two field-effect transistor stages connected which are in a shunt position with respect to the signal paths such that two signal paths are positioned between two field-effect stages which are opposite to each other. At this time, the same voltage is impressed to the signal paths which are in a position opposite to each other among four signal paths, and the control voltage which are complementary to each other is impressed to the adjacent signal paths.