Patent ID: 6163291
Filing Date: 2000-12-19
Classification: H03M

Abstract:
An A/D conversion method, which is an A/D conversion method for successively deciding the digital data for d bits each by successively comparing an input analog voltage and a comparison voltage,having a first step that sets the digital data containing d bits, to a prescribed value,a second step that forms about 2.sup.d +1 comparison voltages in a total voltage range in which each value differs based on the digital data,a third step that selects an upper and lower discriminating voltage and a calculating comparison voltage from the comparison voltages and compares the input analog voltage to these three voltages, on the first comparison the upper discriminating voltage is set to the top of the total voltage range and the lower discriminating voltage is set to the bottom of the total voltage range, the difference between the upper and lower discriminating voltage is a comparison voltage range, on subsequent comparisons the upper and lower discriminating voltage and thus the comparison voltage range vary depending on the previous comparison being normal or abnormal, the subsequent comparison voltage range after a normal comparison is a subset of the previous comparison voltage range and the first comparison will necessarily always be normal, a comparison is abnormal if the input analog voltage is greater than an upper discriminating voltage or less than a lower discriminating voltage of a subsequent comparison voltage range due to fluctuation of the input analog voltage, a subsequent comparison voltage range after an abnormal comparison is set outside the range of the previous comparison voltage range;a fourth step that decides the value of the d bits, based on the comparison result among said comparison voltages when said comparison result is normal,a fifth step that decides the values of the d bits, for this time along with correcting the values of the previous decision bits based on said comparison result when said comparison result is abnormal,a sixth step that discriminates as to whether all of the bits in the digital data have or have not been decided,a seventh step that outputs said decided digital data when all bits of the digital data have been decided,with the processes subsequent to said second step being repeated until the values of all the bits in the digital data are decided.