ANALYSIS OF THE NOISE CHARACTERISTICS OF CMOS CURRENT CONVEYORS

The definition of the current conveyor is reviewed and a multiple-outp ut second generation current conveyor (CCII) is shown to combine the d ifferent generations of current conveyors presently existing. Next, no ise sources are introduced, and a general noise model for the current conveyor is described. This model is used for the analysis of selected examples of current conveyor based operational amplifier configuratio ns and the noise performance of these configurations is compared. Fina lly, the noise model is developed for a CMOS current conveyor implemen tation, and approaches to an optimization of the noise performance are discussed. It is concluded that a class AB implementation can yield a lower noise output for the same dynamic range than a class A implemen tation. For both the class A implementation and the class AB implement ation it is essential to design low noise current mirrors and current sources, and with the class AB design, the current mirror and current source noise can be reduced by using small values of bias current with out compromising the maximum available output current.