High-frequency distortion in emitter-driven variable-gain pairs

Distortion caused by nonzero base or emitter resistance in an emitter-driven pair is analyzed with charge storage effect included in the circuit equations. A closed-form solution, valid for both low and high frequencies, is obtained for the second- and third-order harmonic distortion for the output current using Volterra series representation. The high-frequency distortion is compared with the distortion plot given by Sansen and Meyer (1973). There is some agreement for the third-order harmonic distortion if the value of the frequency parameter B is reduced by a factor of two. For high frequencies and at high attenuations, the asymptotic expression for the maximum distortion is identical with that given by Sansen and Meyer.