analog / digital converter and method of analog / digital conversion.

摘要

The system includes; a voltage conversion circuit (11a, 11b) selectively obtaining at least three kinds of conversion voltages, i.e., a first conversion voltage which is double the input voltage (AIN), a second conversion voltage which subtracts a reference voltage (VR) from the first conversion voltage, and a third conversion voltage which adds the reference voltage to the first conversion voltage; a comparison circuit (CPR1, CPR2) setting at least two decision level voltages (-1/4VR, +1/4VR) and comparing the converted) voltage (VCMP) with each of the decision level voltages; then outputting a command signal as a result of a comparison to the voltage conversion circuit so that the voltage conversion circuit outputs one of the conversion voltages in response to the command signal; and a control circuit (SGT) for changing the connections of switches (S1A...S7B) provided in the voltage conversion circuit in response to the result of the comparison by the comparison circuit.