1. An amplifier comprising: a main amplifier that generates an intermediate amplified signal; a main signal adjuster including at least three parallel signal paths that couple an input signal to the main amplifier, with each of the parallel signal paths including a complex gain adjuster that is controlled by main control inputs; a first subtracter that subtracts a delayed version of the input signal from the intermediate signal, resulting in an error signal; and a main controller that, based on the error signal, generates main control signals which are provided to the main control inputs of the main signal adjuster.