Method and apparatus for compensation of phase distortion in power amplifiers

A power amplifier circuit for amplifying an input signal, said power amplifier circuit comprising:

• an envelope detector for producing an envelope signal from said input signal;
• an envelope amplifier coupled to said envelope detector for producing an amplified envelope signal, wherein said envelope amplifier comprises a class S modulators;
• a scaling amplifier for summing said amplified envelope signal with a nominal gate bias to produce a gate bias signal;
• and
• a power amplifier for amplifying said input signal, wherein said power amplifier is biased with said gate bias signal.

A power amplifier with reduced phase distortion, said power amplifier comprising:

• a driver amplifier stage which receives an input signal;
• a power amplifier stage having an input coupled to an output of said driver amplifier stage, and having an output for producing an output signal;
• a scaling amplifier for modulating a gate bias of said driver amplifier stage;
• an envelope detector for detecting an envelope of the input signal to produce an envelope signal, wherein said scaling amplifier is responsive to said envelope signal;
• and
• an envelope amplifier coupled to said envelope detector, for producing an amplified envelope signal.

A communications device comprising:

• a power amplifier circuit wherein said power amplifier circuit comprises:
• (i) a driver amplifier stage which receives an input signal;
• (ii) a power amplifier stage having an input coupled to an output of said driver amplifier stage, and having an output for producing an output signal;
• (iii) an envelope detector for detecting an envelope of the input signal to produce an envelope signal;
• (iv) an envelope amplifier coupled to said envelope detector, for producing an amplified envelope signal;
• and
• (v) a scaling amplifier for modulating a gate bias of said driver amplifier stage.

In an EER-type amplifier which introduces phase distortion in a signal path, a method of reducing said phase distortion, said method comprising the steps of:

• envelope detecting an input signal to produce an envelope signal;
• amplifying said envelope signal to produce an amplified envelope signal;
• modulating a power amplifier stage with said amplified envelope signal;
• scaling said envelope signal to produce a scaled envelope signal;
• summing said scaled envelope signal with a nominal gate bias signal to produce a driver amplifier gate bias;
• and
• biasing a driver amplifier stage with said driver amplifier gate bias.