Regenerative Modes of Active Networks

An active device with passive imbedding can produce natural frequencies in the right-half plane. In the design of regenerative circuits, it is important to find the permissible location of regenerative modes. In this paper the maximum real part of the natural frequency of an active device under arbitrary passive imbedding is determined. Furthermore, it is shown that this regenerative mode can actually be realized. For the case of a pentode, the required passive network is a gyrator.