مرکز منطقه ای اطلاع رساني علوم و فناوري - Nonlinear Distortion in Feedback Amplifiers

Abstract :

Consider a feedback amplifier $F$ with a nonlinear output device $T_0$ and an open-loop amplifier A having the same gain and the same output device $T_0$ . If the gains of the forward amplifier $u$ and feedback network $\\beta$ are independent of frequency, it is well known that under the usual conditions the nonlinear distortion $\\zeta$ of $F$ due to $T_0$ is related to the nonlinear distortion $\\hat{\\zeta }$ of $A$ by $\\zeta = \\hat{\\zeta }/(1 + u \\beta )$ . In this paper conditions are determined under which a similar formula, namely $\\zeta = (1 + u \\beta )^{-1 \\ast }$ , applies when $u$ and $\\beta$ are strictly stable linear time-invariant amplifiers. The interpretation of the formula is the following: $\\zeta$ is the function of time which is output of an amplifier whose gain is $1/(1 + u \\beta )$ when $\\hat{\\zeta }$ is its input, and $\\hat{\\zeta }$ is the nonlinear distortion of the open-loop amplifier A.