A Stability Test for a Class of Linear, Active Two-Ports with Uncertain Parameters

A new procedure is presented for testing the stability of lumped, linear, active, time-invariant two-ports. The mare advantage of this procedure is that it can consider conditional stability when the passive terminating impedances are limited to only a small subset of all passive impedances represented by the entire right half of the complex plane (RHP). The method can be easily computerized. It is especially useful when only the numerical values of the two-port parameters at various frequencies are known. One version of such a computer program is currently in use at Bell Laboratories for studying the stability properties of two-wire voice-frequency telephone circuits containing E6 type repeaters.