A first to a fourth sampling switch (1a to 1d), a first to a fourth sampling
capacitor (4 to 7), and a first and a second charge redistribution switch (2a, 2b) are provided on the input side of a
differential amplifier (8). A first and a second reset switch (3a, 3b) are provided between the input and the output of the
differential amplifier (8). An input
signal voltage (Vinp) having a positive polarity, a comparison reference
voltage (Vrefn) having a negative polarity, a comparison reference
voltage (Vrefp) having a positive polarity, and an input
signal voltage (Vinn) having a negative polarity are respectively applied through a first to a fourth sampling switch (1a to 1d) to one end of each of the first to the fourth sampling
capacitor (4 to 7). During a reset period, the reset of the
differential amplifier (8) is released after sampling of each voltage is completed, and during a comparison period, the first and the second charge redistribution switch (2a, 2b) are electrically connected.