Amplifier circuits and methods

An amplifier circuit comprising:

• an amplifier input terminal for receiving an input signal;
• a transistor having a gate terminal, drain terminal, and body terminal, the gate terminal being coupled to the amplifier input terminal;
• a load coupled to the drain terminal of the transistor;
• a body conditioning circuit having an input coupled to the amplifier input terminal and an output coupled to the body terminal of the transistor, the body conditioning circuit including a threshold detector to detect an envelope of the input signal and generate a control signal to change the bias current in the amplifier in response to changes in the envelope of the input signal.

A wireless communication system comprising:

• a baseband processor for encoding a communication signal to be transmitted;
• a modulator coupled to the baseband processor for receiving the encoded communication signal and generating an RF signal;
• an RF amplifier coupled to the modulator for receiving the RF signal, the RF amplifier comprising a transistor and a load;
• and
• a body modulation circuit having an input for receiving the encoded communication signal and an output coupled to a body terminal of the transistor.

A method of controlling the transmission of a signal comprising:

• sensing the amplitude of a signal to be transmitted;
• generating a control signal indicating that the amplitude of the signal to be transmitted has changed;
• receiving the signal to be transmitted at the gate of at least one transistor;
• and
• changing the body voltage of the transistor from a first voltage to a second voltage.

In a wireless communication system, a method of transmitting a signal comprising:

• encoding a signal in a baseband processor;
• modulating the encoded signal to produce an RF signal;
• and
• amplifying the signal in an RF amplifier, the amplifier including a transistor and a load;
• wherein, when the RF signal has a first envelope, a body terminal of the transistor is biased to a first voltage, and when the RF signal has a second envelope, the body terminal of the transistor is biased to a second voltage.