NONLINEAR DISTORTION IN FEEDBACK AMPLIFIERS

Consider a feedback amplifier F with a nonlinear output device T sub o and an open loop amplifier A having the same gain and the same output device T sub o. If the gain of the forward amplifier Mu 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 sub o is related to the nonlinear distortion Zeta of A by Zeta Zeta1Mu Beta. In this paper we determine conditions under which a similar formula, namely Zeta 1Mu Beta times Zeta, applies when Mu and Beta are strictly stable linear time invariant amplifiers. The interpretation o the formula is the following Zeta is the function of time which is output of an amplifier whose gain is 1 91Mu Beta when Zeta is its inp t, and Zeta is the nonlinear distortion of the open loop amplifier A. Author