Hitachi-kokusai Electric Inc.

Kokusai Electric Co., Ltd.

Takeshi Ishigami

Kotaro Takenaga

Yoshinari Nanao

Hiroichi Yonenaga

Hiromichi Hayase

In a distortion compensating amplifier that compensates for distortion occurring in main amplifiers, a first amplifying unit amplifies, with a first main amplifier, a first signal consisting of a main signal to be amplified and detects distortion occurring in the first main amplifier, a distortion adjusting unit subjects the distortion detected by the first amplifying unit to vector adjustment, a second amplifying unit combines a second signal consisting of the main signal to be amplified and the distortion supplied from the distortion adjusting unit and amplifies a combined signal with a second main amplifier, and a combining unit combines an amplified signal supplied from the first amplifying unit and an amplified signal supplied from the second amplifying unit.

Distortion compensating amplifier

There is disclosed a feedforward amplifier for compensating for distortion produced in an amplifier. The feedforward amplifier controls the phase in a vector adjuster effectively. The feedforward amplifier has a first variable phase shifter PHor PHfor varying the phase of a signal passed through the first variable phase shifter and a second variable phase shifter PHor PHfor varying the signal passed through the first variable phase shifter in either or both of a distortion detection loop for detecting the distortion and a distortion compensation loop for compensating for the distortion. A phase control portion controls the amount of variation in phase in the first variable phase shifter and values of the amount of variation in phase are concentrated toward either one of relatively-larger directions or relatively-smaller directions, the amount of variation in phase in the second phase shifter is controlled according to the concentrated values.

Feedforward amplifier

A feed forward type distortion compensation amplification apparatus includes a first division unit for dividing an input signal into a first channel signal and a second channel signal, a main amplifier for amplifying the first channel signal, a variable attenuation unit for processing the second channel signal to provide an amplitude adjusted second channel signal, a delay unit for delaying the amplitude adjusted second channel signal, a second division unit for dividing an output signal of the main amplifier into a third channel signal and a fourth channel signal and subtracting one of the third channel signal and the delayed second channel signal from the other to extract a distortion component introduced by the main amplifier, and a distortion compensation unit for removing a distortion component introduced into the fourth channel signal by the main amplifier, by using the distortion component extracted by the second division unit.

Feed forward amplification apparatus for compensating non-linear distortion

The object of this invention is to provide a feedforward amplifier that performs precise distortion compensation on a plurality of signal groups without adopting broadband frequency-band characteristics for the auxiliary amplifier. This is achieved by inputting a plurality of signal groups, each having a different frequency bandwidth respectively. In a distortion detection loop, a main amplifier is used to amplify this plurality of input signal groups and detect the distortion arising in said main amplifier . In a distortion compensation loop the distortion detected in the distortion detection loop is removed from the amplified signal from said main amplifier At this time, the distortion compensation loop has the same number of distortion amplification systems as the number of input signal groups that use the auxiliary amplifiers and to amplify distortion in each input signal group that contains distortion detected by the distortion detection loop, and that removes the sum total of the distortion of each input signal group amplified by this plurality of distortion amplification systems from the amplified signal from the main amplifier

A metal-oxide semiconductor field-effect transistor (MOSFET) amplifier circuit includes a compensation circuit with a low cost MOSFET and a constant current circuit providing a constant drain current of the MOSFET, which maintains an operational point of the amplifier at an optimal state at all times. The MOSFET amplifier circuit includes a first MOSFET, a constant current circuit including a variable resistor, an operational amplifier, a power supply and a resistor, a second MOSFET having a constant current generated by the constant current circuit as a drain current thereof, and a voltage control circuit including operational amplifiers and resistors for applying a gate source voltage of the second MOSFET to the first MOSFET as a gate-source voltage thereof.

Growing community of inventors

Tokyo, Japan

Takeshi Ishigami