Multi stage amplifier

A multi-stage amplifier comprising;

• a first, a second and a third sub-amplifier, each with respective input and output ports;
• and
• the multi stage amplifier also comprising a common output port;
• wherein the output port of the second sub-amplifier is connected via a first connection having a first electrical length L1 to the output port of the first sub-amplifier and is connected via another a second connection having a second electrical length L2 to the common output port, and the output port of the third sub-amplifier is connected via a third connection having a third electrical length L3 to the common output port;
• and
• wherein the electrical lengths L1, L2 of the connections from the second sub-amplifier's output port both to the first amplifier's output port and to the common output port are longer or shorter than one quarter of a wavelength (λ) of the frequency for which the multi-stage amplifier is intended to operate.