Patent ID: 7394417

Claim:
An A/D converter comprising a preamp row including one or more preamps and a comparator row including one or more comparators, wherein each preamp of said preamp row receives, as inputs, a reference voltage or difference-reference voltages and an analog input signal or differential analog input signals and has a positive output terminal and a negative output terminal, said preamp has a function to multiply, by a gain thereof, a potential difference between said reference voltage and said analog input signal or a potential difference between a potential difference between said difference-reference voltages and a potential difference between said differential analog input signals and to output said potential difference having multiplied by the gain from said positive output terminal and said negative output terminal as differential outputs, each comparator of said comparator row is connected to said positive output terminal and said negative output terminal of each preamp, said comparator has a function to compare an output of said preamp with a comparing reference voltage, or to interpolate output voltages of said positive output terminals and said negative output terminals of two or more preamps adjacent to each other and compare said interpolated voltages, each of said preamps is correspondingly provided with a preamp gain adjusting circuit, and said preamp gain adjusting circuit reduces the gain of said corresponding preamp when a preamp positive-negative output potential difference that is a potential difference between said positive output terminal and said negative output terminal of said corresponding preamp exceeds a reference potential.