Patent ID: 7391354
Filing Date: 2008-06-24
Classification: H03M

Abstract:
1. A semiconductor integrated circuit comprising: a successive approximation type A/D converter incorporated therein, including a local D/A converter, wherein a main D/A converter and a sub D/A converter of the local D/A converter are respectively constituted of a capacitance array type D/A converter and a resistance string type D/A converter, wherein the capacitance array type D/A converter used as the main D/A converter is constituted of a plurality of capacitors and a plurality of changeover switches respectively coupled to one ends of the capacitors, and the other ends of the capacitors are commonly coupled to a voltage comparator inputted with each voltage for common connection as a successive reference voltage compared with an input analog signal, wherein one input terminals of the changeover switches are commonly coupled to a first external terminal of the semiconductor integrated circuit in such a manner that the one input terminals of the respective changeover switches are capable of being commonly supplied with an analog reference voltage via a low-pass filter from outside the semiconductor integrated circuit, wherein one capacitor is added to the capacitors of the capacitance array type D/A converter and one end of the one additional capacitor is supplied with each LSB-side successive reference voltage from the sub D/A converter, wherein the resistance string type D/A converter used as the sub D/A converter of the local D/A converter comprises a plurality of resistors connected in series, and a plurality of switches having input terminals coupled to connecting nodes of the resistors, wherein output terminals of the switches are connected in common thereby to generate the LSB-side successive reference voltages from the sub D/A converter out of the commonly-connected output terminals of the switches, and wherein one end of a series connection of the resistors of the resistance string type D/A converter used as the sub D/A converter is coupled to a second external terminal of the semiconductor integrated circuit in such a manner that the one end of the series connection thereof is capable of being supplied with the analog reference voltage from outside the semiconductor integrated circuit.