AD CONVERTER AND SENSOR SYSTEM INCLUDING THE SAME

To achieve the miniaturization.SOLUTION: An input switch unit 2 outputs one output signal V3 selected from a first signal VA input to a first input terminal TA and a second signal VB input to a second input terminal TB. An AD conversion unit 3 includes a DA conversion unit 5, a comparator 7, an integrator 61, and a control unit 4. The DA conversion unit 5 generates a comparison voltage corresponding to target bits from the most significant bit to the least significant bit. The comparator 7 determines the value of the target bit by comparing a difference voltage V4 between the output signal V3 of the input switching unit 2 and the comparison voltage and a reference voltage. The integrator 61 integrates the conversion error after the comparator 7 performs the sequential comparison operation up to the least significant bit. In the first conversion operation in which the AD conversion of the first signal VA1 is performed, the control unit 4 sets the reference voltage when the AD conversion of the first signal VA1 is performed next on the basis of the integration result of the integrator 61, and in the second conversion operation in which the AD conversion of the second signal VA2 is performed, the reference voltage is set to a constant voltage level.SELECTED DRAWING: Figure 1 【課題】小型化を図ること。【解決手段】入力切替部２は、第１入力端子ＴＡに入力される第１信号ＶＡ、及び、第２入力端子ＴＢに入力される第２信号ＶＢから選択した一の出力信号Ｖ３を出力する。ＡＤ変換部３はＤＡ変換部５と比較器７と積分器６１と制御部４とを備える。ＤＡ変換部５は、最上位ビットから最下位ビットまでの対象ビットに対応する比較電圧を発生する。比較器７は、入力切替部２の出力信号Ｖ３と比較電圧との差電圧Ｖ４と基準電圧とを比較することで、対象ビットの値を決定する。積分器６１は、最下位ビットまで比較器７が逐次比較動作を行った後の変換誤差を積分する。制御部４は、第１信号ＶＡ１のＡＤ変換を行う第１変換動作では、積分器６１の積分結果に基づいて次に第１信号ＶＡ１のＡＤ変換を行う場合の基準電圧を設定し、第２信号ＶＡ２のＡＤ変換を行う第２変換動作では、基準電圧を一定の電圧レベルとする。【選択図】図１