Stability of parasitic dynamics at a DC-operating point: topological analysis

The stability of the DC-operating points is discussed. A necessary condition is given for the asymptotic stability of the DC-operating points of a circuit, based on the type of circuit elements and their connections, but not on their parameters. If the condition is not satisfied, there are circuit parameters such that the circuit has an unstable DC-operating point. If the condition is satisfied, the linearized circuit at the DC-operating point has no positive real natural frequencies, but it still could have complex conjugate natural frequencies with a positive real part