PREFERRED CIRCUIT TECHNIQUES FOR TRANSISTOR AMPLIFIERS.

This report describes an investigation of circuit techniques to minimize spurious responses in transistor amplifiers. An investigation was conducted of both bipolar transistor amplifiers and field-effect transistor amplifiers. For bipolar transistor amplifiers, equations were derived which predict harmonic generation, intermodulation, and cross-modulation. These equations include dependence upon circuit configuration common emitter, common base, and common collector, load resistance, source resistance, frequency, feedback, cascading, and bias current and voltage. Extensive measurements verify the validity of the equations with good correlation under nearly all conditions for several transistors 2N2857, 2N3137, 2N3553, 2N3995, TIXS40. For field-effect transistor FET amplifiers, the nonlinear characteristics were determined by measurements of several FETs K1201, K1003, 2N3823, TIXS35. It was shown that a simple graphical analysis can be used to determine the bias conditions for which the nonlinear effects are minimized. The measurements indicate that the FET is probably better than the bipolar transistor for equal transistor dissipation. Since present FETs do not have the dissipation capabilities of bipolar transistors, they are likely to be out-performed by bipolar transistors with higher dissipation capabilities. Author