Signal folding in A/D converters

Signal folding appears in A/D converters (ADCs) in various ways. In this paper, the evolution of this technique is derived from the fundamentals of quantization to obtain systematic insights. We look upon folding as an automatic multiplexing of zero crossings, which simplifies hardware while preserving the high speed and low latency of a flash ADC. By appreciating similarities between the well-known pipeline ADCs, folding ADCs, and ripple through ADCs, this enables the circuit designer to more freely choose the best architecture to meet the specified performance goals. Index Terms--A/D converter, analog encoding, signal folding.