Active linearization for broadband amplifiers

A power amplifier circuit for broadband data communication over a path in a communication network, the power amplifier circuit comprising:

• a first amplifier stage, comprising circuitry including:
• a first transistor, having a signal input node to receive a data signal voltage to be converted by the first transistor into a current to contribute to an output signal current to be provided at a signal output node;
• and.
• a first gain degeneration resistor, coupled to the first transistor and configured to receive a representation of a component of the output signal current provided by the first transistor;
• and
• at least one second amplifier stage, comprising circuitry including:
• a second transistor, coupled to the first transistor to receive an input voltage based on the data signal voltage, and configured to turn on at a larger amplitude of the data signal voltage relative to a smaller amplitude of the data signal voltage to (1) to provide current to at least a portion of the first gain degeneration resistor to reduce a transconductance or other gain of the first transistor;
• and (2) contribute current to the output signal current to help maintain or enhance an overall gain between the signal input node and the signal output node;
• and
• wherein the first gain degeneration resistor includes:
• a first resistance component, arranged to provide a control voltage to turn on the second transistor;
• and
• a second resistance component, arranged to receive current from the second transistor to increase an effective resistance of the second resistance component to reduce the gain of the first transistor.

A power amplifier circuit for broadband data communication over a path in a. communication network, the power amplifier circuit comprising:

• a first amplifier stage, comprising circuitry including:
• a first transistor, having a signal input node to receive a data signal voltage to be converted by the first transistor into a current to contribute to an output signal current to be provided at a signal output node;
• and.
• a first gain degeneration resistor, coupled to the first transistor and configured to receive a representation of a component of the output signal current provided by the first transistor;
• and
• at least one second amplifier stage, comprising circuitry including:
• a second transistor, coupled to the first transistor to receive an input voltage based on the data signal voltage, and configured to turn on at a larger amplitude of the data signal voltage relative to a smaller amplitude of the data signal voltage to (1) to provide current, separately from current provided by the first transistor, to at least a portion of the first gain degeneration resistor to reduce a transconductance or other gain of the first transistor;
• and (2) contribute current to the output signal current to help maintain or enhance an overall gain between the signal input node and the signal output node.