Transistor amplifier performance

Abstract

Summary form only given, as follows. Fundamental restrictions on the gain, bandwidth, and sensitivity which can be achieved in multistage transistor amplifiers arise from the inherent internal feedback and frequency dependency of the device parameters. These gain and bandwidth limitations are discussed in terms of Linvill?s power gain charts and the resistance integral theorem. A new set of charts are then devised which permit rapid evaluation of the effects of load impedance on input impedance at a given frequency. A sensitivity criterion is defined as the percentage change in input impedance for a given change in load impedance. This criterion allows one to plot areas on the charts from which the load impedances must be selected for the required sensitivity. For small sensitivity, a relation between sensitivity and power gain is derived which enables one to determine how much power gain must be lost for a given sensitivity. This information permits direct comparison of neutralized and unneutralized amplifiers. The theory given above serves to specify operating impedances and insertion loss of the interstage and load networks at a set of discrete frequencies in the amplifier pass band. The design of these networks can again be cast in terms of the charts and power gain formulas.