Microwave Circuit Conditional Stability: Two-Parameter Criteria

The purpose of the present work is to introduce two-parameter criteria for unconditional instability and for special cases of conditional stability, which can be particularly interesting for the design of two and three port oscillators. The criteria involve the two-port stability factor K, as was to be expected, and have analogies with the well-known ones for unconditional stability. The mutual relationships existing between the Input and the Output Stability Area, demonstrated in a previous paper, will be used to construct a complete table in which to each of the possible reciprocal positions between stability areas and unit circle, an algebraic criterion corresponds, consisting in the calculation of two simple parameters. Also, limit cases will be analyzed.