Multistage amplifier

A multistage amplifier for amplifying a multicarrier signal including a first component having a first frequency f1 and a second component having a second frequency f2, the multistage amplifier generating an amplified multicarrier signal also including a distortion frequency component that is n times a differential frequency, f2−f1 (n is an integer equal to or greater than 1), and comprising:

• N amplifiers (N is an integer equal to or greater than 2), each amplifier being distinguished as an ith stage amplifier (i is an integer of 1 to N), a (k+1)th stage amplifier being cascaded to a kth stage amplifier (1≤k≤N−1), and each amplifier being configured to amplify the multicarrier signal;
• and
• a compensation circuit minimizing the distortion frequency component and including an input and an output, the input being connected to an output of a jth stage amplifier (j is an integer of 1 to N−1), and the output providing a compensation signal to an input of a (j+1)th stage amplifier or an output of the (j+1)th stage amplifier, wherein the compensation circuit includes
• a filter circuit being connected to the output of the jth stage amplifier and being configured to extract the distortion frequency component,
• a phase shifter circuit being cascaded to the filter circuit, and being configured to shift a phase of an extracted distortion frequency component from the filter circuit, and
• an amplitude adjusting circuit being cascaded to the phase shifter circuit and being configured to adjust an amplitude of an extracted and phase-shifted distortion frequency component from the phase shifter circuit and generate the compensation signal.