Patent ID: 7091897

Claim:
An analog-to-digital converting circuit comprising: a first analog-to-digital converting part for converting an input analog value into a digital value of a predetermined number of bits; a digital-to-analog converting part for converting the digital value output from said analog-to-digital converting part into an analog value; a subtracting part for outputting a difference between the analog value output from said digital-to-analog converting part and the analog value input to said first analog-to-digital converting part; an amplifying part for amplifying an output from said subtracting part; a feedback path for feeding an output from said amplifying part to said first analog-to-digital converting part; a switch for enabling and disabling feedback to said first analog-to-digital converting part on said feedback path; a second analog-to-digital converting part for converting the analog output from said amplifying part into a digital value of a predetermined number of bits; a branch path for causing the output from said amplifying part to branch from said feedback path to said second analog-to-digital converting part; a control part for controlling on/off of said switch, wherein said control part effects control so that a total of (n+1) conversion steps are performed by said first analog-to-digital converting part and said second analog-to-digital converting part in a total of n cycles, by turning on and off said switch at regular intervals.