Nonlinear distortion attenuation using H∞ techniques

The authors consider a nominally linear system and investigate the deviation of the output due to a nonlinear deviation in the characteristic of a nominally linear component of the system. They introduce a feedback compensator and show that the closed-loop distortion is related to open-loop distortion through the so-called sensitivity matrix given by S=(I+GK^-1 where G is the nominal transfer matrix of the system and K is the feedback compensator. H^∞ optimization theory is applied to minimize the H^∞ norm of S. The Glover-Doyle algorithm is utilized to find the optimal compensator that generates minimum nonlinear distortion