Noise Analysis of Circuits with General Topology and Arbitrary Representation

A method for noise analysis of microwave multiports with general internal topology is presented. The multiport circuit is seperated into the connection circuit and the circuit elements. Based upon the digraph representation of the connection circuit the scattering matrix of the connection circuit is computed from the fundamental cut set matrix and the fundamental loop matrix of the connecting circuit. Using this digraph and a canonical description of the signal and noise properties of the circuit elements the S-matrix of the multiport and the correlation matrix of its external equivalent noise sources may be determined directly. The circuit may consist of noisy two-terminal elements as well as noisy multiport elements.