A/D Converter Fundamentals And Trends

• Quantization is a search process ranging from the most efficient serial binary search to the fastest brute-force parallel search. • Parallel search is reduced in complexity by signal folding but at the cost of delicate analog signal processing (e.g. MDAC). • Serial binary search combined with comparator reuse results in the most efficient • SAR ADCs at the expense of conversion rate. • SAR ADC speed can be increased by time-interleaving as many quantizers as needed, with the mismatch error digitally calibrated. • Digital calibration and error correction overheads diminish in advanced CMOS processes, leading to SAR ADC popularity. • SAR ADC is sub-ranged for resolution and pipelined for speed, while the switching scheme is optimized for power efficiency.