System and method for IM3 reduction and cancellation in amplifiers

A discrete amplifier for canceling at least one distortion component at the output of the discrete amplifier comprising:

• a. an input port for receiving a first signal;
• b. an output port for outputting a second signal that is related to said first signal;
• c. a first branch operatively connected to said input and said output ports and a second branch in parallel with said first branch and operatively connected to said input and said output ports,
• d. a first biasing circuit operatively connected to said first branch for biasing said first branch into a first mode of operation;
• e. a second biasing circuit operatively connected to said second branch for biasing said second branch into a second mode of operation;
• f. a sensing circuit that senses said first signal and causes at least one of said first and said second biasing circuits to change the operating mode of its respective branch by adjusting at least one of a biasing circuit current and impedance so as to maximize the cancellation of said at least one distortion component,
• wherein said first mode of operation and said second mode of operation are chosen so that said at least one distortion component in said second signal is substantially reduced.

A circuit for canceling at least one distortion component at the output of the circuit comprising:

• a. a power splitter having
• i. a first input port,
• ii. a first output port, and
• iii. a second output port;
• wherein a first signal is input on said power splitter first input port and is split into a second signal at said power splitter first output port and a third signal at said power splitter second output port;
• b. a power combiner having
• i. a first input port,
• ii. a second input port, and
• iii. a first output port,
• c. a first amplifier having
• i. an input port coupled to said power splitter first output port, and
• ii. an output port coupled to said power combiner first input port;
• d. a second amplifier in parallel with said first amplifier, said second amplifier having
• i. an input port coupled to said power splitter second output port, and
• ii. an output port coupled to said power combiner second input port;
• e. at least one biasing circuit operatively connected with one of said first and said second amplifiers for biasing said one of said first and said second amplifiers in a different class of operation than the other of said first and said second amplifiers;
• and
• f. at least one control logic circuit for sensing said first signal and for causing at least one of
• i. a size of said one of said first and said second amplifiers to change based on said first signal, and
• ii. a magnitude of a biasing level of said one of said first and said second amplifiers to change based on said first signal,
• wherein a fourth signal is output from said power combiner first output port having at least one distortion component reduced.

A discrete amplifier for canceling at least one distortion component at the output of the discrete amplifier comprising:

• a. a first stage having at least a first branch and a second branch in parallel with one another;
• b. a second stage having at least a third branch and a fourth branch in parallel with one another;
• c. a first biasing circuit operatively coupled to said first stage first branch, said first biasing circuit being configured to provide a first impedance and a first biasing level that drives said first branch into a first mode of operation;
• d. a second biasing circuit operatively coupled to said first stage second branch, said second biasing circuit being configured to provide a second impedance and a second biasing level that drives said second branch into a second mode of operation that is different from said first mode of operation;
• e. a third biasing circuit operatively coupled to said second stage third branch, said third biasing circuit being configured to provide a third impedance and a third biasing level that drives said third branch into a third mode of operation;
• f. a fourth biasing circuit operatively coupled to said second stage fourth branch, said fourth biasing circuit being configured to provide a fourth impedance and a fourth biasing level that drives said fourth branch into a fourth mode of operation that is different from said third mode of operation,
• wherein
• said first and said second bias circuit impedances at baseband frequencies are different,
• said third and fourth bias circuit impedances at baseband frequencies are different, and
• are chosen so that at least one distortion component is substantially cancelled at a respective output of at least one of said first stage and said second stage.