Separation of Quantization and Control in Optimal Analog to Digital   Converters
  In this paper we prove optimality of a certain class of Analog to Digital Converters (ADCs), which can be viewed as generalized Delta-Sigma Modulators (DSMs), with respect to a performance measure that can be characterized as the worst-case average intensity of the signal representation error. An analytic expression for the ADC performance is given. Furthermore, our result proves separation of quantization and control for this class of ADCs subject to some technical conditions. 
Mitra Osqui and Alexandre Megretski
math.OC