New distortion measurement method for booster amplifiers

The usual method of distortion measurement of an amplifier in a feedback loop involves breaking the loop, which may change the dc and (nonlinear) interstage loading conditions. A new method is presented and proven with theory and experiment, permitting distortion measurement of a final or booster stage within an amplifier. The new method does not require breaking of the feedback loop. Measurements are carried out with linear and nonlinear loudspeaker load.