A pipeline analog-to-digital converter is disclosed which includes at least one periodic unit consisting of two adjacent stages that jointly use two capacitor networks of the same structure. Each of the capacitor networks includes two identical capacitors, two switches and four terminals. On/off states of the switches and interconnection configuration of the terminals are controlled by clock signals to switch the periodic unit between four possible connection configurations. During operation of the periodic unit, when the upstream stage is in a sampling phase that involves one of the capacitor networks as well as a reference capacitor, the downstream stage uses the other of the capacitor networks to conduct residue amplification; and on the other hand, when the upstream stage is using one of the capacitor networks for residue amplification, the downstream stage relies also on this capacitor network for sampling, leaving the other of the capacitor networks idle.