Intermodulation distortion detection in a power shared amplifier network

Abstract

An intermodulation distortion (IMD) detection system improves IMD reduction capability of power shared linear amplifier networks. In one embodiment, first and second power sharing networks, preferably Butler Matrices, are provided with a plurality of linear amplifier circuits coupled therebetween. A plurality of input signals are applied to respective input ports of the first power sharing network, with a portion of each input signal amplified by each amplifier circuit and then recombined in the second power sharing network so that each amplified input signal appears at only one output port of the second power sharing network. An antenna coupled to each of these output ports then radiates the amplified signal energy associated with one of the input signals. A test signal, which may be a dual tone signal, is applied to another input port of the first power sharing network, where it is split and amplified by each amplifier circuit. Each amplifier circuit includes detection circuitry for detecting IMD energy of the test signal produced in the amplifier, which is also indicative of the IMD energy generated due to the amplification of the input signals. The amplified test signal is then recombined by the second power sharing network so that it appears only at one output port, where it is terminated.