Hitachi, Ltd.

Renesas Technology Corp.

Irei Kyu

Satoshi Tanaka

Shigeki Koya

Takashi Oshima

Kenji Maio

Yukinori Akamine

Manabu Kawabe

Koji Maeda

Takeshi Doi

This invention provides a receiver in which the calibration time by repeated operations to correct phase mismatch and amplitude mismatch between I and Q signals can be reduced. The receiver comprises mixers which convert received RF signals into quadrature modulated IF signals, signal paths which filter and amplify and output the quadrature modulated signals output from the mixers, a calibration circuit which calibrates phase and amplitude mismatches between the I and Q components of the quadrature modulated signals output through the signal paths, a frequency converter which, when the mixers or the signal paths selected output calibration signals with IF frequency instead of the quadrature modulated signals, converts the calibration signals into those with a frequency higher than IF frequency, and an arithmetic operation circuit which calculates phase and amplitude mismatches from the calibration signals output by the frequency converter and outputs calculation results. The calibration circuit executes calibration, using the calculation results.

Receiver, receiving method and portable wireless apparatus

A 90-degree phase delay power divider part PSPD is connected to an input side of a carrier amplifier Ampand a peak amplifier Amp, and a variable electric length power combiner VTLis connected to an output side thereof. A control signal Sig is applied through a control terminal Ctrl of the variable electric length power combiner VTL, and adjustment is performed in correspondence to a carrier frequency band of a carrier signal RFs so that an electric length of the variable electric length power combiner VTLbecomes nearly 90 degrees. As a result, an electric length of an output power combining circuit of a Doherty type amplifier can be made variable, and a power-added efficiency can be enhanced for a multi-band or broad band.

Power amplifier and transmitter

In order to rapidly control the gains of a plurality of variable gain amplifiers VGAs, each of gain control circuits is configured to determine a gain to be set therein, based on gain control information received from other gain control circuits existing in its preceding stage or stages and the signal level detected by a level detector circuit connected thereto. By carrying out such gain control, a total application gain is stabilized more quickly by gain control. Therefore, even in receiving systems that the preparation period for reception is very short, desired gain control is achieved within this period and stable data reception can be performed.

Variable gain amplifier circuit and gain control method thereof

Growing community of inventors

Kokubunji, Japan

Irei Kyu