Power amplifier

A transmitter circuit, comprising:

• a power amplifier, the power amplifier comprising:
• at least one field-effect transistor having a gate terminal and a bulk terminal, wherein the at least one field-effect transistor is configured to receive an input voltage at the gate terminal and a dynamic bias voltage at the bulk terminal;
• and
• a bias-voltage generation circuit,
• wherein the input voltage is a linear function of an input signal,
• wherein the bias-voltage generation circuit is configured to generate the dynamic bias voltage as a nonlinear function of an envelope of the input signal, and
• wherein the bias-voltage generation circuit comprises a digital signal-processing circuit configured to determine a metric of nonlinearity of the power amplifier, and when the determined metric of nonlinearity exceeds a threshold, the digital signal-processing circuit is further configured to adjust coefficients of the nonlinear function, to reduce the determined metric of nonlinearity.

A communication apparatus, comprising:

• a transmitter circuit having a power amplifier, the power amplifier comprising:
• at least one field-effect transistor having a gate terminal and a bulk terminal, wherein the at least one field-effect transistor is configured to receive an input voltage at the gate terminal and a dynamic bias voltage at the bulk terminal;
• and
• a bias-voltage generation circuit,
• wherein the input voltage is a linear function of an input signal,
• wherein the bias-voltage generation circuit is configured to generate the dynamic bias voltage as a nonlinear function of an envelope of the input signal, and
• wherein the bias-voltage generation circuit comprises a digital signal-processing circuit configured to determine a metric of nonlinearity of the power amplifier, and when the determined metric of nonlinearity exceeds a threshold, the digital signal-processing circuit is further configured to adjust coefficients of the nonlinear function, to reduce the determined metric of nonlinearity.

A method of controlling a power amplifier for a transmitter circuit, wherein the power amplifier comprises at least one field-effect transistor having a gate terminal and a bulk terminal, and wherein the at least one field-effect transistor is configured to receive an input voltage at the gate terminal and a dynamic bias voltage at the bulk terminal;

• the method comprising:
• generating the input voltage as a linear function of an input signal;
• generating the dynamic bias voltage as a nonlinear function of an envelope of the input signal;
• determining a metric of nonlinearity of the power amplifier;
• and
• adjusting coefficients of the nonlinear function, to reduce the determined metric of nonlinearity, when the determined metric of nonlinearity exceeds a threshold.