High-speed analog-digital converter having a signal folding structure improved by reducing the number of elementary cells

The invention relates to high-resolution analog-digital converters using so-called folding differential amplifier structures composed of differential circuits (crossed differential pairs) and of loads (cascode transistors). The folding structure according to the invention comprises, in the case where it is desired to produce four curves folded at two periods in the useful range of voltages to be converted, four folding blocks (one per curve). The first comprises 7 differential circuits and eight loads, the end loads not being linked to the output of the block. The other blocks comprise 6 differential circuits and eight loads, the last load of each block not being linked to the output of this block. Gains are achieved in terms of bulk, consumption and operating speed, with respect to existing structures.