Segmented power amplifier and method of control

An amplifier comprising:

• a bias circuit adapted to selectively provide bias signals responsive to a bias control signal;
• two or more amplifier segments selectively enabled via said bias signals, each comprising a plurality of transistor amplification stages and each adapted to provide an amplified output signal based on amplifying a common source signal when said amplifier segment is enabled;
• and
• a common output connected to an output from each said amplifier segment, said common output adapted to provide a final output signal based on combining said amplified output signals
• wherein said two or more amplifier segments comprise at least one first amplifier segments designed for low-power source signal amplification and at least one second amplifier segments designed for higher-power source signal amplification, and said transistor amplification stages each comprise a stage input, stage output, and a hetero-junction bipolar transistor (HBT) amplifier disposed between said stage input and said stage output.

A method of operating a power amplifier, said method comprising:

• providing a segmented power amplifier comprising two or more selectively enabled amplifier segments, each segment adapted to amplify a source signal with a known maximum segment output power when enabled;
• determining a desired overall amplifier maximum output power;
• enabling one or more of said amplifier segments in a combination corresponding to said desired overall amplifier maximum output power;
• and
• combining an amplified output signal from each said enabled amplifier segment to form a final amplifier output signal having said desired overall amplifier maximum output power;
• wherein said amplifier segments each comprise a like number of one or more transistor amplifier stages and each said transistor amplifier stage is fabricated such that one or more transistors comprising each said transistor amplifier stage operate with a desired emitter current density when biased to said transistor operating point.

A method of operating a power amplifier, said method comprising:

• providing a segmented power amplifier comprising two or more selectively enabled amplifier segments, each segment adapted to amplify a source signal with a known maximum segment output power when enabled;
• determining a desired overall amplifier maximum output power;
• enabling one or more of said amplifier segments in a combination corresponding to said desired overall amplifier maximum output power;
• and
• combining an amplified output signal from each said enabled amplifier segment to form a final amplifier output signal having said desired overall amplifier maximum output power;
• wherein one or more of said two or more amplifier segments is designed to operate with low levels of quiescent current when enabled, as compared to one or more other said amplifier segments comprising said segmented power amplifier.