Patent ID: 7061419
Filing Date: 2006-06-13
Classification: H03M

Abstract:
1. An A/D converter comprising: a reference voltage generator circuit for generating a plurality of reference voltages; a plurality of differential amplifier circuits, provided so as to correspond to the reference voltages generated by the reference voltage generator circuit, each for receiving an associated one of the reference voltages and a common input signal voltage, amplifying a voltage difference between the associated reference voltage and the input signal voltage and outputting complimentary non-inversion and inversion output voltages; a plurality of voltage comparator circuits, provided so as to correspond to the differential amplifier circuits, each for comparing the non-inversion and inversion output voltages from an associated one of the differential amplifier circuits and outputting a digital signal corresponding to a relationship between the non-inversion and inversion voltages in terms of voltage level; a coding circuit for coding a plurality of digital signals output from the plurality of voltage comparator circuits and outputting as a single digital data signal corresponding to the input signal voltage; and a regulator circuit for regulating the non-inversion and inversion output voltages of the plurality of differential amplifier circuits so that the non-inversion and inversion voltages are in an input range for the plurality of voltage comparator circuits, wherein the regulator circuit includes: a differential amplifier circuit replica, formed so as to have the same circuit configuration and shape as those of the differential amplifier circuits, for receiving an equal voltage to a voltage supplied to the differential amplifier circuits and outputting a common mode voltage, and an operational amplifier circuit for generating a feedback control voltage so that the common mode voltage output from the differential amplifier circuit replica matches a predetermined reference voltage and sending the feedback control voltage back to the differential amplifier circuit replica, and wherein the feedback control voltage from the operational amplifier is sent back to the plurality of differential amplifiers.