CONSTANT CURRENT SOURCE, RAMP VOLTAGE GENERATION CIRCUIT, AND A/D CONVERTER,申请号JP20070018973-传众专利搜索

CONSTANT CURRENT SOURCE, RAMP VOLTAGE GENERATION CIRCUIT, AND A/D CONVERTER

申请公布号：JP2008187432(A)

申请号：JP20070018973

申请日期：2007.01.30

申请公布日期：2008.08.14

申请人：

SHARP CORP

发明人：MARUYAMA MASAHIKO

分类号：H03K4/71;H03M1/56

主分类号：H03K4/71

摘要：PROBLEM TO BE SOLVED: To provide a ramp voltage generation circuit suitable for an A/D converter for suppressing variation caused in a digital value to be obtained by an A/D converting operation. SOLUTION: This ramp voltage generation circuit is provided with: a stabilization voltage source Vref; an operational amplifier AMP1 in which a voltage V<SB>REF</SB>to be output from the voltage source Vref is input to a non-inversion input terminal, and an inversion input terminal is connected to a switched capacitor equivalent resistor Req; and a transistor MNSF for performing the conduction control of currents Ick to the equivalent resistance Req on the basis of the output voltage of the operational amplifier AMP1, wherein both ends of a capacitive load Cint to be charged/discharged on the basis of currents Iint2 to be generated as the result of current-mirroring of the currents Ick are connected to the output terminal and inversion input terminal of the operational amplifier AMPint, and the voltage of the stabilization voltage source Vc is applied from the non-inversion input terminal, and the output voltage of the operational amplifier AMPint is output to the outside as a ramp voltage. COPYRIGHT: (C)2008,JPO&INPIT