Evaluation of Transistor Neutralization Networks

The neutralization technique selected for use with transistor IF amplifiers will have a considerable effect upon the gain and stability of the amplifier. Attention is concentrated here upon the matrix methods of neutralization which unilateralize the transistor. The matrix parameters of the unilateralized device are derived for each of the four types of unilateralization-
z, y, h
, and
g
. These are expressed in terms of the transistor two-port parameters and the elements of the neutralizing network. The influence of the network on the driving point immittances, maximum transducer gain, and stability can then be considered. (Unilateralization does not necessarily insure unconditional stability.) The effects of non-ideal transformers used for the
z
and
y
types of neutralization are evaluated. Applications of these equations, over the frequency range from 30 to 80 mc, using measured parameters of the type 3N25 tetrode, are discussed.