Gain, sensitivity and stability of linear two-port amplifiers
A. Singhakowinta · Spiral (Imperial College London) · 1964
In this thesis matched and mismatched two-port amplifiers with general feedback are analysed, compared and discussed in terms of the basic parameters of the two-ports.It is shown that the matched amplifier is generally superior to the mismatched amplifier, both in gain-sensitivity performance and in ease of design.The power gain of the matched amplifier can be expressed simply in terns of only two basic parameters, which are independently variable; one of these is real and the other complex.The relation between the power gain and the parameters is displayed geometrically in the forms of the Inverse Gain Space and the Inverse Gain Chart.Both of these geometrical representations find useful applications in amplifier design, particularly since an area or volume of spread in these representations tends to remain invariant in size as it is moved about by feedback.The gain-sensitivity performance of the matched amplifier is investigated in detail for various types of spreads of basic parameters.Sensitivity figures are defined to facilitate consideration of amplifier sensitivity performance, and it is found that gain-sensitivity figure products tend to remain constant in the stable region except for the area close to the border of marginal stability.Since basic parameters are so useful in amplifier consideration, new methods for measuring and determining them are described and verified experimentally.These measurements can be done using both lumped and distributed measuring circuits.Finally, new techniques for synthesizing amplifiers to have given sensitivity performance and frequency response are described.These techniques are illustrated by experiments using physical transistors.