ABSTRACT
FPGAs were originally conceived as pure digital devices, not including any analog circuitry, such as input or output analog interfaces, which had to be built outside the FPGA whenever required. In contrast, analog circuitry is necessary for many FPGA applications (in general, but particularly in the case of industrial embedded systems) where, therefore, the need for ADCs and DACs is unavoidable. Even if control logic for external ADCs and DACs can be usually implemented using distributed logic inside the FPGA, eliminating the need for additional chips implementing glue logic and delays associated with external interconnections limit sampling or reconstruction frequency and may cause synchronization problems, thus having a negative impact on performance.
