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 rectifier circuit configured to generate a rectified input voltage;
• and
• an amplifier circuit operatively connected to the rectifier circuit and configured to generate the dynamic bias voltage based on the rectified input voltage,
• wherein the amplifier circuit is a variable-gain amplifier circuit, and
• wherein the power amplifier comprises a control circuit configured to tune the gain of the amplifier circuit.

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 rectifier circuit configured to generate a rectified input voltage;
• and
• an amplifier circuit operatively connected to the rectifier circuit and configured to generate the dynamic bias voltage based on the rectified input voltage,
• wherein the amplifier circuit is a variable-gain amplifier circuit, and
• wherein the power amplifier comprises a control circuit configured to tune the gain of the amplifier circuit.