Power amplifier and wireless communication device
There are provided a power amplifying transistor, a bias circuit which supplies a bias current to the base of the power amplifying transistor, a current mirror circuit which detects a peak value of the collector voltage of the power amplifying transistor, and a control circuit which, when the peak value of the collector voltage becomes higher than a voltage set in advance, controls the bias circuit to increase the bias current.
1. A power amplifier comprising:
a power amplifying transistor;
a bias circuit which supplies a bias current to the base of the power amplifying transistor;
a current mirror circuit which detects a peak value of the collector voltage of the power amplifying transistor; and
a control circuit which, when the peak value of the collector voltage becomes higher than a voltage set in advance, controls the bias circuit to increase the bias current.
2. A power amplifier comprising:
a power amplifying transistor;
a bias circuit which supplies a bias current to the base of the power amplifying transistor;
a current mirror circuit which detects a peak value of the collector voltage of the power amplifying transistor; and
a control circuit which raises a load curve of the power amplifying transistor when the peak value of the collector voltage becomes higher than a voltage set in advance.
3. The power amplifier according to claim 1 , wherein the current mirror circuit has a choke inductor for removing high-frequency components.
4. The power amplifier according to claim 2 , wherein the current mirror circuit has a choke inductor for removing high-frequency components.
5. The power amplifier according to claim 1 , wherein the current mirror circuit has a notch filter for removing high-frequency components.
6. The power amplifier according to claim 2 , wherein the current mirror circuit has a notch filter for removing high-frequency components.
7. A wireless communication device comprising:
an antenna terminal for performing transmission and reception of signals;
a baseband signal processing section which demodulates and decodes a received signal, and which encodes and modulates a signal to be transmitted;
an RF circuit which converts a signal output from the baseband signal processing section into a signal of a predetermined frequency; and
a power amplifier which amplifies a signal output from the RF circuit, the power amplifier having:
a power amplifying transistor;
a bias circuit which supplies a bias current to the base of the power amplifying transistor;
a current mirror circuit which detects a peak value of the collector voltage of the power amplifying transistor; and
a control circuit which, when the peak value from the current mirror circuit becomes higher than a voltage set in advance, controls the baseband signal processing section to reduce the power of the signal input from the RF circuit to the power amplifier.