Nonlinear distortion in common-emitter transistor amplifiers operated in the normal domain

Three nonlinear-distortion sources are analysed separately for polarity and magnitude of harmonics. If magnitudes are small, the resultant harmonic from these sources is the vector sum of its separated magnitudes. Universal charts are computed, to design amplifier circuits with simultaneous zero second and third harmonics. Experiments on an OC44 confirmed the theory, giving 2.5 mW with second to sixth harmonics better than ¿75 dB, power gain 40 dB, and no feedback or push-pull.