Tdk Corporation

Atsushi Ajioka

Atsushi Tsumita

Tomohiko Shibuya

Sadaharu Yoneda

Yoshihiro Suzuki

Masashi Katsumata

Tomihiko Shibuya

A magnetic head has a magnetic head slider that includes a recording element that generates a recording signal magnetic field, a microwave magnetic field generating element that generates a microwave magnetic field, a terminal electrode, and a first transmission line that interconnects the terminal electrode and the microwave magnetic field generating element. A second transmission line is connected to the terminal electrode, the second transmission line being used to transmit a microwave signal from the outside of the magnetic head slider to the magnetic head slider. A capacitor connected to the first transmission line is provided between the terminal electrode and the microwave magnetic field generating element. Accordingly, in the magnetic head, a microwave signal is efficiently propagated.

Magnetic head, head gimbal assembly, and magnetic recording and reproducing apparatus

There is provided a high-frequency amplifier including a divider, a plurality of amplifiers for amplifying a high-frequency signal distributed by the divider and outputting the amplified high-frequency signal, a combiner for combining amplified high-frequency signals, a base substrate, a conductor pattern that is connected to a ground end of each of the amplifiers, and a ground electrode. Each of the conductor patterns has a first conductive portion. A slot is disposed between the two conductor patterns connected to the corresponding adjacent amplifiers. Between the adjacent amplifiers, two vias are formed so that the slot is sandwiched between the vias. One of the two conductor patterns is connected to the ground electrode via one of the two vias, and the other one of the conductor patterns is connected to the ground electrode via the other one of the two vias.

High-frequency amplifier

A high-frequency amplifier circuit includes a balanced-unbalanced converter converting a single-ended signal into differential signals. The output of a first amplifier amplifying the single-ended signal is connected to the signal terminal on the unbalanced side of the balanced-unbalanced converter. The input of a second amplifier amplifying one of the differential signals is connected to one signal terminal on the balanced side of the balanced-unbalanced converter. The input of a third amplifier amplifying another of the differential signals is connected to another signal terminal on the balanced side of the balanced-unbalanced converter. An impedance element is inserted between an element on the balanced side of the balanced-unbalanced converter and a ground.

High-frequency amplifier circuit, semiconductor device, and magnetic recording and reproducing device

Since a high-frequency signal that is output from a high-frequency oscillator circuit section is detected in a detector circuit and a bias of a negative voltage is supplied from a bias circuit section to the high-frequency amplifier circuit section with a detection voltage that is detected, a negative power supply circuit such as a DC/DC converter or a peripheral circuit is not required, and since a negative bias voltage can be supplied to a high-frequency amplifier circuit, downsizing can be achieved with a low cost.

The problem to be solved is to alleviate the distortion characteristic of an amplifier and to prevent the drop in gain with respect to a low-level high-frequency signal. A bias control circuit () for controlling the bias of an amplifier () which amplifies a high-frequency signal is provided herein with a detector () for detecting the envelope of the high-frequency signal, a first bias circuit () for supplying a constant bias current to the amplifier () and a second bias circuit () for supplying a bias current that varies with the variation of the level of the envelope of the high-frequency signal to the amplifier.

Bias control circuit

A high frequency amplifier is characterized wherein a power amplification element and at least one of temperature compensation elements are adjacently provided on a first semiconductor layer, a first wiring pattern connected to the power amplification element, a second wiring pattern connected to the temperature compensation element, and a ground electrode are provided on at least one of second semiconductor layers existing in layers different from the first semiconductor layer, and the ground electrode is formed on the second semiconductor layer corresponding to a region that substantially projects a crevice part on which the temperature compensation element and the power amplification element are provided, on the same plane as the first semiconductor element.

High frequency amplifier

A small-sized, front-end module is offered which is for use in a wireless communication device such as a mobile phone and which can suppress harmonics to a sufficiently low level. The front-end module has at least a switching circuit for switching one antenna between a transmiting system and a receiving system, a power amplifier for power-amplifying a transmission signal, and a low-pass filter inserted between the switching circuit and power amplifier. These components are integrated. A first kind of harmonics is produced from the switching circuit toward the power amplifier and reflected by the low-pass filter. A second kind of harmonics is produced from the power amplifier toward the antenna. A third kind of harmonics is produced from the switching circuit toward the antenna. The third kind of harmonics is canceled by the reflected first kind of harmonics and the second kind of harmonics.

Growing community of inventors

Tokyo, Japan

Atsushi Ajioka