Active predistorting linearizer with agile bypass circuit for safe mode operation

A predistorter for predistorting a RF signal subsequently injected in an amplifier, comprising:

• a hybrid coupler comprising a RF input constituting an input of the predistorter supplied with the RF signal, a RF output constituting an output of the predistorter for supplying a predistorted version of the RF signal, a direct port, and a coupled port;
• a first diode having an anode connected to said direct port and a cathode connected to the ground;
• a second diode having an anode connected to said coupled port and a cathode connected to the ground;
• and
• a controllable biasing-voltage supply connected to said direct port and to said coupled port, thereby supplying said direct and coupled ports with a controllable biasing voltage;
• whereby, in operation, the predistorter produces a controllable predistortion of the RF signal related to the controllable biasing voltage to cancel a distortion subsequently produced by the amplifier.

A predistorter for predistorting a RF signal subsequently injected in an amplifier, comprising:

• a hybrid coupler comprising a RF input constituting an input of the predistorter supplied with the RF signal, a RF output constituting an output of the predistorter for supplying a predistorted version of the RF signal, a direct port, and a coupled port;
• first and second diodes connected between the direct port and the ground, said first and second diodes being connected in head to tail configuration;
• third and fourth diodes connected between the direct port and the ground, said third and fourth diodes being connected in head to tail configuration;
• and
• a controllable biasing-voltage supply connected to the direct port and to the coupled port, thereby supplying the direct and coupled ports with a controllable biasing voltage;
• whereby, in operation, the predistorter produces a controllable predistortion of the RF signal related to the controllable biasing voltage to cancel a distortion subsequently produced by the amplifier.

A predistorter for predistorting a RF signal subsequently injected in an amplifier, comprising:

• a hybrid coupler comprising a RF input constituting an input of the predistorter supplied with the RF signal, a RF output constituting an output of the predistorter for supplying a predistorted version of the RF signal, a direct port, and a coupled port;
• a first diode having an anode connected to the direct port and a cathode connected to the ground;
• a first matching circuit and a second diode connected in series between the direct port and the ground, said second diode having a cathode connected to the ground;
• a third diode having an anode connected to the coupled port and a cathode connected to the ground;
• a second matching circuit and a fourth diode connected in series between the coupled port and the ground, said fourth diode having a cathode connected to the ground;
• and
• a controllable biasing-voltage supply connected to the direct port and the coupled port, thereby supplying the direct and coupled ports with a controllable biasing voltage;
• whereby, in operation, the predistorter produces a controllable predistortion of the RF signal related to the controllable biasing voltage to cancel a distortion subsequently produced by the amplifier.

A predistorter for predistorting a RF signal subsequently injected in an amplifier, comprising:

• a hybrid coupler comprising a RF input constituting an input of the predistorter supplied with the RF signal, a RF output constituting an output of the predistorter for supplying a predistorted version of the RF signal, a direct port, and a coupled port;
• a first transistor connected between the direct port and the ground;
• a second transistor connected between the coupled port and the ground;
• and
• a controllable biasing-voltage supply connected to the first transistor and the second transistor, thereby supplying the first and second transistors with a controllable biasing voltage;
• whereby, in operation, the predistorter produces a controllable predistortion of the RF signal related to the controllable biasing voltage to cancel a distortion subsequently produced by the amplifier.

A predistorting linearizer channel amplifier for processing an input signal subsequently supplied to a power amplifier, comprising:

• a controllable input variable-attenuator and drive-amplifier circuit supplied with the input signal to attenuate and amplify said input signal;
• a predistorter comprising a controllable phase-shifting and amplitude-adjusting path supplied with the attenuated and amplified input signal to distort said attenuated and amplified input signal and produce a predistorted output signal;
• a controllable output variable-attenuator and drive-amplifier circuit supplied with the predistorted output signal to attenuate and amplify the predistorted output signal before supplying said predistorted output signal to the power amplifier;
• a phase-shifting and amplitude-adjusting controller connected to the controllable input variable-attenuator and drive-amplifier circuit, the controllable phase-shifting and amplitude-adjusting path, and the controllable output variable-attenuator and drive-amplifier circuit;
• and
• a bypass extending in parallel with the series circuit including the serially interconnected input variable-attenuator and drive-amplifier circuit, controllable phase-shifting and amplitude-adjusting path, and output variable-attenuator and drive-amplifier circuit, said bypass defining a bypass circuit established in response to a fault condition in said series circuit to bypass the faulty series circuit.