Transistor-feedback-amplifier design

Formulas are given to help in the estimation of the positions of poles and zeros of the open-loop gain of an uncorrected transistor amplifier. Design curves are provided to enable the determination of a modified pole-zero configuration which will yield a desired gain and phase margin against oscillation. A synthesis procedure is described which yields a network making the necessary modifications to the pole-zero configuration. Formulas for element values enable the process to be carried out with simple arithmetic calculations for a type of amplifier commonly encountered. This process does not involve the usual practice of measuring the open-loop frequency response of the uncorrected amplifier and then correcting this to approximate to Bode´s ideal-loop-gain characteristic. This correction usually involves either fitting a required loss curve with a rational function or an equally tedious `cut-and-try¿ experimental process.