This paper studies the problem of sensor noise in dithered adaptive systems. It has been previously demonstrated that dithered adaptive systems may have superior sensitivity reduction properties than linear time invariant (LTI) feedback systems. However it is shown in this paper that the dithered designs which contain a saturating nonlinear element may have sensor noise properties worse than the LTI design for the same uncertainty or disturbance problem, despite the considerably smaller bandwidth of the nonlinear dithered design.
Two new versions of dithered adaptive systems are developed, where the nonlinear element in the main loop is eliminated, and noise is considerably reduced. Bandwidth and sensor noise effect improvement are now both significantly less than in the LTI design. Systematic design procedures are presented for satisfying quantitative system specifications for a large class of feedback problems. The resulting designs are optimum with respect to loop bandwidth and close to optimum for sensor noise effect. A numerical example not solvable with LTI design techniques is shown illustrating the design technique. *