Power amplifier and semiconductor integrated circuit
In general, according to one embodiment, a power amplifier includes an envelope detector, a limiter, and a combiner. The envelope detector is configured to sense an envelope component of an input signal. The limiter includes a PMOS (Positive channel Metal Oxide Semiconductor) transistor and an NMOS (Negative channel Metal Oxide Semiconductor) transistor. The PMOS transistor is configured to sense a phase component of the input signal. The phase component has a second-order distortion controlled within a predetermined range with respect to the input signal. The NMOS transistor is configured to sense a phase component of the input signal. The phase component has the same second-order distortion as the phase component sensed by the PMOS transistor. The combiner is configured to combine the envelope component sensed by the envelope detector and the phase component sensed by the limiter to generate an output signal.
1. A power amplifier comprising:
an envelope detector configured to sense an envelope component of an input signal;
a limiter comprising a PMOS (Positive channel Metal Oxide Semiconductor) transistor configured to sense a first phase component of the input signal and an NMOS (Negative channel Metal Oxide Semiconductor) transistor configured to sense a second phase component of the input signal, the first phase component having a first second-order distortion controlled within a predetermined range with respect to the input signal, the second phase component having a second second-order distortion;
a combiner configured to combine the envelope component sensed by the envelope detector and the phase component sensed by the limiter to generate an output signal; and
a bias controller configured to control a bias of the limiter to cancel the first second-order distortion by the second second-order distortion, the bias controller comprising a current sensor configured to sense an operating current of the limiter, a controller configured to convert an analog signal indicating the operating current sensed by the current sensor into a digital signal and generate a control parameter based on the digital signal, and a bias generator configured to generate a bias current or a bias voltage based on the control parameter.
2. The amplifier of claim 1 , wherein the controller comprises a memory capable of storing data, writes a first operating current sensed by the current sensor to the memory, generating the control parameter for changing the bias current, calculates an operating current difference between a second operating current corresponding to the bias current generated based on the control parameter and the first operating current stored in the memory when the second operating current is sensed by the current sensor, and generates the control parameter for generating the bias current corresponding to a minimum value of the operating current difference.
3. The amplifier of claim 1 , wherein the bias controller comprises:
a multiplier configured to calculate a product of the envelope component sensed by the envelope detector and the operating current sensed by the current sensor, wherein
the bias generator generates the bias current or the bias voltage based on the product calculated by the multiplier.
4. A semiconductor integrated circuit comprising:
a power amplifier comprising:
an envelope detector configured to sense an envelope component of an input signal;
a limiter comprising a PMOS (Positive channel Metal Oxide Semiconductor) transistor configured to sense a first phase component of the input signal and an NMOS (Negative channel Metal Oxide Semiconductor) transistor configured to sense a second phase component of the input signal, the first phase component having a first second-order distortion controlled within a predetermined range with respect to the input signal, the second phase component having a second second-order distortion;
a combiner configured to combine the envelope component sensed by the envelope detector and the phase component sensed by the limiter to generate an output signal;
a bias controller configured to control a bias of the limiter to cancel the first second-order distortion by the second second-order distortion, the bias controller comprising a current sensor configured to sense an operating current of the limiter, a controller configured to convert an analog signal indicating the operating current sensed by the current sensor into a digital signal and generate a control parameter based on the digital signal, and a bias generator configured to generate a bias current or a bias voltage based on the control parameter; and
a transceiver configured to send and receive a radio frequency signal based on an output signal of the power amplifier.
5. The circuit of claim 4 , wherein the controller comprises a memory capable of storing data, writes a first operating current sensed by the current sensor to the memory, generating the control parameter for changing the bias current, calculates an operating current difference between a second operating current corresponding to the bias current generated based on the control parameter and the first operating current stored in the memory when the second operating current is sensed by the current sensor, and generates the control parameter for generating the bias current corresponding to a minimum value of the operating current difference.
6. The circuit of claim 4 , wherein the bias controller comprises:
a multiplier configured to calculate a product of the envelope component sensed by the envelope detector and the operating current sensed by the current sensor
wherein the bias generator generates the bias current or the bias voltage based on the product calculated by the multiplier.
7. The circuit of claim 4 , the transceiver adopts OFDM (Orthogonal Frequency Division Multiplexing) system.