Method of linearizing a non-linear amplifier, linearization circuit and amplifier including a circuit of this kind

A linearizer circuit for a non-linear amplifier, adapted to operate at microwave frequencies, including phase non-linearity correction means and amplitude nonlinearity correction means, said phase correction means including:

• an electrically controlled phase-shifter controlled by a first control signal,
• a phase comparator having at least two inputs and one output and producing at said output a signal corresponding to the relative phase difference between the signals at said two inputs,
• a first input coupler on the input side of said nonlinear amplifier and a first output coupler on the output side of said non-linear amplifier, said first input coupler providing a first input coupler signal representative of the phase of said input side signal before amplification to one of said inputs of said phase comparator and said first output coupler providing a signal representative of the phase of said output side signal after amplification to the other of said two inputs of said phase comparator, said output of said phase comparator being coupled as said first control signal to the control input of said phase-shifter in order to control the phase of said input signal in such manner as to cancel any phase non-linearity due to non-linear amplification;
• and said amplitude non-linearity correction means including:
• a power supply modulator for modulating a power supply of said non-linear amplifier, the output voltage of said power supply modulator being electrically controlled by a second control signal applied to a control input of said modulator,
• a power comparator having at least two inputs and one output, said power comparator receiving at its inputs said second input coupler and second output coupler signals and providing at its output a power control signal corresponding to a difference in amplitude of said second input and output coupler signals
• a second input coupler on the input side of said nonlinear amplifier and a second output coupler on the output side of said non-linear amplifier,
• an automatic gain control (AGC) amplifier in series with and on the input side of said non-linear amplifier, the gain of said AGC amplifier being electrically controllable in accordance with said power control signal,
• said second input coupler providing a second input coupler signal representative of the amplitude of said input side signal as said second control signal to said control input of said modulator in order to control the supply voltage of said non-linear amplifier,
• said second input coupler also providing said second input coupler signal to one of said inputs of said power comparator and the second output coupler providing a second output coupler signal representative of the amplitude of the output signal after amplification to the other of said inputs of said power comparator, producing a signal representative of an input-output amplitude error between the second input and second output coupler signals, said error signal being applied to the control input of said automatic gain control amplifier in order to control the amplitude of the input signal in such manner as to cancel any amplitude non-linearity due to non-linear amplification.