Power amplifying device and power amplifying method
A power amplifying device includes an amplifier that amplifies a signal which is input in accordance with a voltage signal which is supplied to the amplifier, a voltage control section that controls the voltage signal in accordance with a transmission signal, a distortion compensating section that executes a distortion compensating process on the transmission signal by giving a value indicative of a reverse characteristic of the amplifier to the transmission signal in advance and inputs an output signal obtained by executing the distortion compensating process into the amplifier, an amplitude detecting section that detects an amplitude of the transmission signal, and a timing adjusting section that adjusts timings of the output signal and the voltage signal so that a value relating to the distortion compensating process meets a given condition when a detected value of the amplitude of the transmission signal is less than a given value.
1. A power amplifying device comprising:
an amplifier that amplifies a signal which is input in accordance with a voltage signal which is supplied to the amplifier;
a voltage control section that controls the voltage signal in accordance with a transmission signal;
a distortion compensating section that executes a distortion compensating process on the transmission signal by giving a value indicative of a reverse characteristic of an input-to-output characteristic of the amplifier to the transmission signal in advance and inputs an output signal obtained by executing the distortion compensating process into the amplifier;
an amplitude detecting section that detects an amplitude of the transmission signal;
a timing adjusting section that adjusts timings of the output signal and the voltage signal so that a value relating to the distortion compensating process executed on the transmission signal meets a given condition when a detected value of the amplitude of the transmission signal is less than a given value, said given value being less than a value of a maximum amplitude of the transmission signal; and
a coefficient updating section that sequentially updates a distortion compensation coefficient according to the reverse characteristic of the input-to-output characteristic of the amplifier based on the output signal and a feedback signal of an output from the amplifier;
wherein the distortion compensating section performs an arithmetic operation in advance using the distortion compensation coefficient on the transmission signal as the distortion compensating process, and
wherein the timing adjusting section adjusts the timings so as to decrease variance of the distortion compensation coefficient for the transmission signal when the detected value of the amplitude of the transmission signal is less than the given value, and the timing adjusting section calculates the variance of the distortion compensation coefficient using a value obtained by dividing the output signal by the transmission signal as a value corresponding to the distortion compensation coefficient for the transmission signal.
2. The power amplifying device according to claim 1 , wherein
the timing adjusting section adjusts the timings so as to reduce the amplitude of the output signal when the detected value of the amplitude of the transmission signal is less than the given value.
3. The power amplifying device according to claim 1 , further comprising:
an inclination detecting section that detects inclination information of the transmission signal, wherein
the timing adjusting section determines a direction in which the timings are adjusted in accordance with the inclination information.
4. The power amplifying device according to claim 1 , further comprising:
an inclination detecting section that detects inclination information of the transmission signal, wherein
the timing adjusting section determines a direction in which the timings are adjusted in accordance with the inclination information of the transmission signal obtained when the detected value of the amplitude of the transmission signal is less than the given value and the variance of the distortion compensation coefficient is increased.
5. A power amplifying method comprising:
controlling a voltage signal which is supplied to an amplifier in accordance with a transmission signal;
executing a distortion compensating process on the transmission signal by giving, in advance, a value indicative of a reverse characteristic of an input-to-output characteristic of the amplifier to the transmission signal;
inputting, into the amplifier, an output signal obtained by executing the distortion compensating process and amplifying the output signal using the amplifier;
detecting an amplitude of the transmission signal;
adjusting timings of the output signal and the voltage signal so that a value relating to the distortion compensating process executed on the transmission signal meets a given condition when a detected value of the amplitude of the transmission signal is less than a given value, said given value being less than a value of a maximum amplitude of the transmission signal; and
sequentially updating a distortion compensation coefficient according to the reverse characteristic of the input-to-output characteristic of the amplifier based on the output signal and a feedback signal of an output from the amplifier;
wherein the executing includes performing an arithmetic operation in advance using the distortion compensation coefficient on the transmission signal, and
wherein the adjusting includes:
adjusting the timings so as to decrease variance of the distortion compensation coefficient for the transmission signal when the detected value of the amplitude of the transmission signal is less than the given value, and
calculating the variance of the distortion compensation coefficient using a value obtained by dividing the output signal by the transmission signal as a value corresponding to the distortion compensation coefficient for the transmission signal.
6. The power amplifying method according to claim 5 , wherein
the adjusting includes adjusting the timings so as to reduce the amplitude of the output signal when the detected value of the amplitude of the transmission signal is less than the given value.
7. The power amplifying method according to claim 5 , further comprising:
detecting inclination information of the transmission signal, wherein
the adjusting includes determining a direction in which the timings are adjusted in accordance with the inclination information.
8. The power amplifying method according to claim 5 further comprising:
detecting inclination information of the transmission signal, wherein
the adjusting includes determining a direction in which the timings are adjusted in accordance with the inclination information of the transmission signal when the detected value of the amplitude of the transmission signal is less than the given value and the variance of the distortion compensation coefficient is increased.