US Patent 7791413 Linearizing technique for power amplifiers

Embodiments described herein relate to amplification circuits. In some embodiments the amplification circuit includes a power amplifier, a feedforward error compensation loop, and phase feedback and amplitude feedback error compensation loops nested within the feedforward loop. The two nested feedback loops provide a “pre-cleaning” action, which reduces the amount of rejection required in the feedforward loop. In some embodiments, the amplification circuit includes a power amplifier and an enhanced feedforward loop comprising a phase control circuit that maintains a phase balance needed to reduce distortion in the output signal of the amplification circuit. In some embodiments, the amplification circuit includes a power amplifier, a feedforward error compensation loop, and phase feedback and amplitude feedback error compensation loops nested within the feedforward loop and the feedforward loop comprises the phase control circuit.