An embodiment of an amplifier system includes a modifiable signal adjustment device with an RF signal adjustment circuit coupled between first and second nodes. The RF signal adjustment circuit includes an adjustable phase shifter and an adjustable attenuator coupled in series with each other. The device also includes a memory and a controller circuit. The controller circuit retrieves a phase shift value and an attenuation value from the memory. The controller circuit then controls the adjustable phase shifter to apply a phase shift corresponding to the phase shift value to an input RF signal received at the first node, and controls the adjustable attenuator to apply an attenuation corresponding to the attenuation value to the input RF signal. Applying the phase shift and the attenuation results in an output RF signal at the second node.